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Marriage Equality Policy Diffusion

Summary and Keywords

Marriage equality movements have been successful in achieving policy change in an increasing number of states. Hence, a growing body of scholarship has explored institutional and cultural factors that influence activists’ tactics and messaging and, in turn, contribute to marriage equality policy diffusion. Democracies with parliamentary, presidential, and semi-presidential systems, federal and unitary states with varying levels of centralization, and the presence or absence of constitutional anti-discrimination protections provide social movements with divergent political opportunity structures, contributing to dynamics in their tactical choices. In addition, the type of electoral system and party system, the presence of political parties that are movement allies, the use of conscience votes, the level of party discipline, the presence of out LGBT elected officials and straight political allies, and the degree of political will to enact policy change also impact activists’ strategic calculations. Finally, the use of personalized narratives in advocates’ messaging, the framing of marriage equality and LGBT rights as human rights norms, the adoption of family values frames to coopt opponents’ messaging, and the use of homonationalist versus homophobic discourses to justify policymaking decisions regarding same-sex marriage are explored. This article provides a comprehensive review of state-of-the-art research concerning all of the states that have legalized same-sex marriage as well as a detailed analysis of the mechanisms used to achieve policy change. After examining how different explanatory factors perform in accounting for the dynamics in marriage equality activism and policy convergence across a broad range of national contexts, new directions for future scholarship are suggested.

Keywords: marriage equality, same-sex marriage, LGBT rights, LGBT politics and policy, policy diffusion, policy convergence, social movement, activism, advocacy, political opportunity structure

Marriage Equality Policy Diffusion, Activism, and Mechanisms for Policy Change

Marriage equality policy diffusion refers to the increase in the number of states and subnational jurisdictions of certain states adopting same-sex marriage (Mitchell & Petray, 2016). The term policy convergence has also been used to describe the growing number of countries adopting same-sex union laws, as well as the increasing similarity of these laws cross-nationally (Paternotte & Kollman, 2013). Policy diffusion regarding marriage equality is still ongoing, and there is no clear time limitation or other demarcation regarding the endpoint of this process. Dynamics in the political opportunity structure that marriage equality activists face in different institutional contexts are integral in their decisions about tactical repertoires to pursue in each country and thus impact the mechanisms by which marriage equality is achieved (Díez, 2018; Smith, 2008, 2018; Valiquette & Waring, 2018). Further, the diffusion of norms, discourse, and activists’ strategies cross-nationally may also influence policy diffusion. Namely, the growing acceptance of marriage equality and LGBT rights as a norm, the ways in which messaging and framing about same-sex marriage has been shared, and the spread of tactics used by marriage equality activists may have contributed to the growing adoption of same-sex marriage (Friedman, 2012; Kollman, 2007; Paternotte, 2015).

The experiences of early adopter countries like the Netherlands led several scholars to suggest that an incremental approach to policy change would be pursued by other states, with decriminalization preceding the adoption of non-discrimination laws and followed by the legalization of same-sex marriage (Waaldijk, 2004). In addition, the adoption of civil unions and their normalization was assumed to accelerate the legalization of same-sex marriage, as civil unions could help quell fears, increase contact with loving same-sex couples, and increase public support for marriage equality (Aloni, 2010). While some countries have indeed followed incremental approaches, there has been considerable variation in the timing and sequencing of LGBT policy changes. In fact, some countries that have legalized same-sex marriage, have refrained from adopting other types of LGBT rights policies. Although some states that adopted civil unions proceeded to legalize same-sex marriage in short order, other states that adopted civil unions have been very slow or unwilling to embrace marriage equality, in part because there are certain countries in which same-sex couples in civil unions receive the same benefits as opposite-sex couples in marriages (Aloni, 2010). However, in other states, registered partnerships offer fewer benefits and fail to address parental rights (Perelli-Harris & Sánchez Gassen, 2012). LGBT activists in countries like Argentina and Ireland were thus divided over whether to support civil partnership legislation as a step toward marriage or whether to oppose it as a lesser, imperfect alternative that failed to address other issues (Díez, 2018; Neary, 2016). The incremental approach to change does help account for the pathways to marriage equality pursued by early-adopter social welfare states that prioritize equality (Friðriksdóttir, 2014).

However, in regions like Eastern Europe, incremental approaches have not been successful in leading to marriage equality, as most countries have gone only so far as to decriminalize homosexuality and adopt non-discrimination laws, but are unwilling to legalize same-sex unions (Bodnar & Śledzińska-Simon, 2014). Incrementalism also does a poor job accounting for the sequence of policy changes in countries like the United States, in which marriage has been legalized in relatively short order following decriminalization but in which federal non-discrimination protections are still lacking (Aloni, 2010). Smith (2008) argues that the delay in decriminalizing homosexuality in the United States created hurdles in achieving the recognition of other LGBT rights like same-sex marriage and non-discrimination protections. Admittedly, the campaign focused on decriminalization helped lead to the development of very well-funded, professionalized, and specialized national LGBT rights organizations in the United States (Smith, 2008). However, resource constraints and the stigma of criminalization made it difficult to advocate for other issues, and the movement encountered many obstacles to policy change, resulting in a longer campaign to achieve marriage equality compared to other states (Smith, 2008, 2018).

Hence far, same-sex marriage has been legalized in the following countries: Argentina, Australia, Belgium, Brazil, Canada, Colombia, Denmark (and its autonomous territory of Greenland), Finland, France, Germany, Iceland, Ireland, Luxembourg, Malta, the Netherlands, New Zealand, Norway, Portugal, Slovenia, South Africa, Spain, Sweden, the United Kingdom of Great Britain (including England, Scotland, and Wales but not Northern Ireland), the United States, and Uruguay. Legislation, litigation, and tools of direct democracy such as referendums, plebiscites, and ballot initiatives have all been used as mechanisms to achieve marriage equality in these countries. In addition, court decisions are in the process of leading to marriage equality in Austria, Costa Rica, Mexico, and Taiwan. This article focuses on countries that have adopted marriage equality or are in the process of legalizing same-sex marriage.

Table 1 summarizes each country’s political system and electoral system, the year marriage equality was adopted nationally and the year this policy change was effective, the tactics used by activists in the battle for marriage equality, and the mechanisms by which marriage equality was achieved at the national level. Tactics used in the battles for marriage equality as well as the impetus for policy change were coded for each country using news coverage and government documents. Tactics are included if proponents or opponents of marriage equality used them either successfully or unsuccessfully at the national or state/provincial levels. Some strategies were used to support or oppose marriage equality before the legalization of same-sex marriage, and others were used to defend, overturn, or limit same-sex marriage after its legalization. The mechanism by which marriage equality was achieved at the national level is the tactic or combination of tactics that resulted in marriage equality nationally or the tactic that is in the process of leading to the legalization of same-sex marriage. Tactics used in civil union campaigns that preceded the marriage equality movement were excluded, as were tactics used for related issues like same-sex adoption. The CIA World Factbook was used to code political systems and electoral systems and was corroborated by other cross-national data on political institutions.

Table 1. Marriage Equality Activists’ Tactics and Mechanisms for Policy Change

Country

Political System

Electoral System (for Unicameral Legislature or for Lower Chamber in a Bicameral Legislature)

Year of Policy Change

Year Policy Effective

Tactics Used by Proponents and Opponents of Marriage Equality

Mechanism for Policy Change at National Level

Proposing Legislation

Filing Litigation

Holding a Referendum, Plebiscite, or Ballot Initiative

Pass Bill

Court Ruling

Supportive Vote in Referendum or Plebiscite

Argentina

Federal Presidential Republic

Proportional Representation

2010

2010

X

X

*

X

Australia

Federal Parliamentary Democracy Under a Constitutional Monarchy

Majority/Plurality (Ranked Choice Voting)

2017

2017

X

X

X

X

X

Austria

Federal Parliamentary Republic

Proportional Representation

2017

TBD (2019 or earlier)

X

X

X **

Belgium

Federal Parliamentary Democracy Under a Constitutional Monarchy

Proportional Representation

2003

2003

X

X

X

Brazil

Federal Presidential Republic

Proportional Representation

2013

2013

X

X

X

Canada

Federal Parliamentary Democracy Under a Constitutional Monarchy

Majority/Plurality

2005

2005

X

X

*

X

Colombia

Presidential Republic

Proportional Representation

2016

2016

X

X

X

Costa Rica

Presidential Republic

Proportional Representation

2018

TBD

X

X

X **

Denmark

Parliamentary Democracy Under a Constitutional Monarchy

Proportional Representation

2012

2012

X

X

X

Greenland, autonomous territory of Denmark

Proportional Representation

2015

2016

X

X

Finland

Parliamentary Republic

Proportional Representation

2015

2017

X

X

*

X

France

Semi-Presidential Republic

Majority/Plurality (Two-Round System)

2013

2013

X

X

*

X

Germany

Federal Parliamentary Republic

Mixed Member Proportional

2017

2017

X

X

X

Iceland

Parliamentary Republic

Proportional Representation

2010

2010

X

X

X

Ireland

Parliamentary Republic

Proportional Representation (Multi-Winner Ranked Choice Voting)

2015

2015

X

X

X

X

X

Luxembourg

Parliamentary Democracy Under a Constitutional Monarchy

Proportional Representation

2014

2015

X

X

*

X

Malta

Parliamentary Republic

Proportional Representation (Multi-Winner Ranked Choice Voting)

2017

2017

X

*

X

Mexico

Federal Presidential Republic

Mixed Member Proportional

2015

TBD (but de facto since 2015)

X

X

*

X **

Netherlands

Parliamentary Democracy Under a Constitutional Monarchy

Proportional Representation

2000

2001

X

X

X

New Zealand

Parliamentary Democracy Under a Constitutional Monarchy

Mixed Member Proportional

2013

2013

X

X

*

X

Norway

Parliamentary Democracy Under a Constitutional Monarchy

Proportional Representation

2008

2009

X

X

Portugal

Semi-Presidential Republic

Proportional Representation

2010

2010

X

X

*

X

Slovenia

Parliamentary Republic

Proportional Representation

2016

2017

X

X

X

X

South Africa

Parliamentary Republic

Proportional Representation

2006

2006

X

X

X

X

Spain

Parliamentary Democracy Under a Constitutional Monarchy

Proportional Representation

2005

2005

X

X

X

Sweden

Parliamentary Democracy Under a Constitutional Monarchy

Proportional Representation

2009

2009

X

X

X

Taiwan

Semi-Presidential Republic

Mixed Member Proportional

2017

TBD (2019 or earlier)

X

X

*

X **

United Kingdom (Great Britain but not Northern Ireland)

Parliamentary Democracy Under a Constitutional Monarchy

Majority/Plurality

England and Wales

2013

2014

X

X

*

X

Scotland

2014

2014

X

*

X

United States

Federal Presidential Republic

Majority/Plurality

2015

2015

X

X

X

X

Uruguay

Presidential Republic

Proportional Representation

2013

2013

X

X

X

(*) Countries in which some states or provinces legalized same-sex marriage earlier than it was legalized nationally.

(**) States in which referendums or plebiscites were called for but were not ultimately held.

(***) States in which same-sex marriage is not yet legal at the national level but essential policy changes have occurred that are in the process of leading to marriage equality nationally.

Many states are in the midst of active campaigns for same-sex marriage, and thus the number of states with marriage equality is likely to continue growing. For example, in Northern Ireland, a bill to legalize same-sex marriage has been introduced to the House of Commons and House of Lords, a previous court ruling regarding same-sex marriage is on appeal, and there have been calls to follow Ireland in having a referendum. It is also noteworthy that a 2018 decision by the Inter-American Court of Human Rights regarding Costa Rica requires 15 additional states (Barbados, Bolivia, Chile, the Dominican Republic, Ecuador, El Salvador, Guatemala, Haiti, Honduras, Mexico, Nicaragua, Panama, Paraguay, Peru, and Suriname) to change their laws to legalize same-sex marriage, although it is likely that the court ruling will face considerable resistance in these highly religious states. Further, a decision from the European Court of Justice is pending, regarding a case involving a Romanian and American bi-national couple who were married in Belgium but were denied spousal residency rights in Romania. If the European Court of Justice follows the recommendation issued by the Belgian advocate general, as is customary, then it is possible all member states of the European Union in which same-sex marriage has not yet been legalized could be required to recognize the rights of same-sex spouses married in states in which marriage equality has been adopted. Such a decision would create pathways for relationship recognition in Eastern European, Southern European, and Mediterranean member states that have been reluctant to legalize same-sex marriage (Bulgaria, Croatia, Cyprus, Czech Republic, Estonia, Greece, Hungary, Italy, Latvia, Lithuania, Poland, Romania, and Slovakia). Romania is planning to host a referendum to change their constitution to ban same-sex marriage, a tactic other states may use to challenge supranational court decisions regarding marriage equality.

Many studies have explored the legalization of same-sex marriage cross-nationally as well as within particular countries. This article reviews past scholarship concerning marriage equality movements and policy convergence regarding same-sex marriage, assessing the impact of institutional and cultural factors on the strategies and messaging used by activists to achieve marriage equality. First, a detailed analysis of the impact of institutional factors on activists’ tactical repertoires and the mechanisms used to achieve policy change is presented, along with a comprehensive review of research concerning the states that have legalized same-sex marriage. Factors examined include the type of political system (parliamentary, presidential vs. semi-presidential), the level of centralization in federal versus unitary states, the presence of constitutional anti-discrimination protections, the type of electoral system and party system, the role of political parties as movement allies, conscience votes, party discipline, the role of out LGBT elected officials and political allies, and the political will to enact policy change. Next, the impact of cultural factors on activists’ messaging and framing as well as the diffusion of norms and discourse regarding same-sex marriage is explored, including the use of personalized narratives in marriage equality messaging, framing of marriage equality and LGBT rights as a human rights norm, the use of family values frames to coopt opposition counterframes, and the use of homonationalist versus homophobic discourses to rationalize policymaking regarding same-sex marriage. While there is some large-n cross-national research on marriage equality activism and policy diffusion, most of the scholarship tends to involve single or comparative case studies that focus on particular causal factors in distinct national and temporal contexts and may not generalize well to other states. Although these empirical analyses often test competing hypotheses, many causal factors merit further investigation, and additional large-n cross-national research as well as experimental research is needed. After examining how different explanatory factors perform in accounting for the dynamics in marriage equality activism and policy diffusion across a broad range of national contexts, the article concludes by suggesting directions for further research.

Parliamentary, Presidential, and Semi-Presidential Systems

Parliamentary, presidential, and semi-presidential systems provide divergent political opportunity structures to marriage equality movements and thus may influence the tactics used by activists as well as the pace of policy change. Smith suggests that institutional differences account for the accelerated pace of change regarding marriage equality in Canada’s parliamentary system, compared to the more prolonged process in the US presidential system. These institutional differences influenced activists’ strategies, with the Canadian context allowing more efficient legal campaigns and lobbying at the national level and the American context requiring protracted state-by-state campaigns involving litigation, legislation, and ballot initiatives or referenda and culminating in federal litigation (Smith, 2008, 2018). In Canada’s parliamentary system, the fusion of legislative and executive power, unified government with both branches controlled by the same party, and strong executive influence by the prime minister and cabinet increase the potential for affirmative government decisions regarding pending LGBT rights litigation and support for the passage of equality legislation such as the Civil Marriage Act. Moreover, the Liberal Party, which was a historic supporter of human rights, was successful in drawing voters’ support just as the LGBT rights movement gained momentum, and there were many potential allies to target via lobbying and grassroots mobilization. However, stronger party discipline also created challenges in cultivating influence within Canadian parties. Smith argues that the concentration of power, accountability, and blame in the executive of parliamentary systems leads governments to avoid backlash by developing policies that enable them to deflect the blame to provinces or the courts. Hence, while the Liberal government argued against same-sex marriage in litigation in Ontario and British Columbia, it did not appeal court decisions in those cases and ultimately asked the Supreme Court of Canada to review the constitutionality of same-sex marriage in 2004. While the partisan environment in Canada was favorable to the LGBT movement, court decisions at the provincial and federal levels were key in driving the government to legislate for marriage equality nationally in a short time frame.

In comparison, in the US presidential system, the separation of powers between the legislative, executive, and judicial branches and frequent periods of divided government resulted in gridlock in passing federal LGBT rights legislation (Smith, 2008, 2018). Further, the Republican Party, which was not a historic supporter of LGBT rights, was ascendant as the LGBT rights movement gained in strength, and this rightward shift limited the number of potential allies for the movement to target via grassroots campaigns and lobbying. In fact, this political context facilitated the passage of legislation antithetical to LGBT rights, as the federal Defense of Marriage Act (DOMA) was passed when both chambers of Congress were under Republican control and was subsequently approved by President Bill Clinton, a Democrat. In the United States, although states’ jurisdiction over marriage was reinforced by the federal DOMA, the constitutionality of state and federal laws regarding marriage could be challenged in state and federal courts and eventually be appealed to the Supreme Court for judicial review. This institutional climate led marriage equality activists to conduct a resource-intensive campaign focusing first on winning marriage at the state-level using legislation, litigation, and direct democracy and focusing later on achieving marriage equality at the federal level using litigation.

Smith (2008) originally predicted a long-term campaign for American marriage equality that might follow the model of the 35-year struggle for decriminalization, and she suggested that policy change could be thwarted by an increasingly conservative Supreme Court. At the time her work was published, many scholars felt that the legalization of same-sex marriage in Massachusetts had driven forth a harmful backlash and were therefore pessimistic about the pace of policy change and the odds of success. In retrospect, federal marriage equality arrived in the United States much more quickly than Smith had anticipated, but she was correct in her prediction (2018) that it would require a state-by-state battle involving various tactics and culminating in a US Supreme Court decision. By 2012, same-sex marriage was legalized via legislation, litigation, and even ballot initiatives and referendums in Connecticut, the District of Columbia, Iowa, Maine, Maryland, New Hampshire, New York, Vermont, and Washington. As state-level litigation was appealed to federal courts, two cases regarding same-sex marriage were appealed to the US Supreme Court in 2013. While the Hollingsworth v. Perry case regarding Proposition 8 was instrumental in legalizing same-sex marriage in California, the United States v. Windsor decision struck down section 3 of DOMA, leading to federal recognition of marriage, regardless of whether couples reside in states that recognize their marriage. A flurry of post-Windsor litigation between 2013 and 2015 helped increase the number of states with marriage equality to nearly three dozen. Finally, the 2015 US Supreme Court decision in Obergefell v. Hodges legalized same-sex marriage nationally, when the court ruled that state-level bans on same-sex marriage were unconstitutional because they violate the Due Process and Equal Protection clauses of the Fourteenth Amendment of the Constitution.

Smith has made a tremendous contribution in exploring how the institutional differences across two North American political systems influence tactics used by activists as well as the trajectories of policy change. In order to explore the impact of political systems on policy change, the tactics used to achieve marriage equality across all the countries that have legalized same-sex marriage are compared. To begin, legislation was used as a mechanism to achieve marriage equality in most parliamentary democracies under a constitutional monarchy (Australia, Belgium, Canada, Denmark and its autonomous territory of Greenland, Luxembourg, the Netherlands, New Zealand, Norway, Spain, Sweden, and the following states in the United Kingdom: England, Scotland, and Wales) as well as most parliamentary republics with largely ceremonial presidents (Finland, Germany, Iceland, Ireland, Malta, Slovenia, and South Africa).

In 2005, the South African Constitutional Court ruled that existing marriage legislation was unconstitutional and gave the legislature one year to modify the law or, if they failed to do so, same sex marriage would be legal at the end of that time frame; as a result, in 2016, the Civil Union Act was passed and signed into law. Similarly, a 2017 Constitutional Court decision in Austria legalized same-sex marriage as of 2019, unless equal marriage legislation is passed earlier. Even though legislation was the main pathway to same-sex marriage in parliamentary systems, earlier litigation paved the way for legislation in all but a handful of these countries, while in other cases like Denmark and Spain, subsequent litigation affirmed the constitutionality of equal marriage legislation (Sénac, 2018).

In Ireland, 62% of voters in a May 2015 referendum amended the Constitution to recognize marriages regardless of partners’ sex, and thus, in October 2015, parliament passed legislation that implemented this policy change. Likewise, 61% of voters in a fall 2017 non-binding mail-in plebiscite in Australia approved changing the law to allow same-sex marriage, and after these results were announced, equal marriage legislation was passed by parliament in December 2017. Slovenia is the only country in which voters have used a referendum to reject equal marriage legislation; the fact that the 2015 referendum proceeded even after the Constitutional Court declared it illegal is indicative of the strong opposition to LGBT rights in Eastern Europe. Surprisingly, a new bill was passed in 2016 that legalized same-sex marriage in Slovenia, although parenting rights like same-sex adoption and in vitro fertilization were prohibited. The use of referendums to block same-sex marriage was debated but ultimately not pursued by activists in several other parliamentary systems (Canada, Finland, Luxembourg, Malta, New Zealand, and the United Kingdom).

In addition, two states with semi-presidential systems (France and Portugal) ultimately achieved marriage equality via legislation. Although litigation helped pave the path to marriage equality in both of these states, it has only played a crucial role in leading to policy change in Taiwan. A 2017 Constitutional Court decision in Taiwan requires equal marriage legislation to be developed within two years or else same-sex marriage will be legalized at the end of that time frame. In all three semi-presidential systems, opponents have considered using referendums as a mechanism to block policy change.

Finally, two presidential systems (Argentina and Uruguay) achieved marriage equality nationally via legislation, and three presidential systems (Brazil, Colombia, and the United States) achieved marriage equality nationally via court decisions. However, both legislation and litigation were used as tactics by marriage equality activists in each of these presidential systems. While Brazil has already legalized marriage equality via a 2013 National Justice Council ruling, efforts are underway to approve equal marriage legislation. In several presidential systems (Costa Rica and Mexico), court decisions are in the process of leading to marriage equality.

Following the decision by the Inter-American Court of Human Rights, same-sex marriage became a wedge issue in the spring 2018 presidential campaign in Costa Rica. The National Restoration party candidate Fabricio Alvarado Muñoz tried to make the election a referendum on same-sex marriage, appealing to a conservative backlash at the imposition of values change and perceived threats to traditional family values and gender norms. He worked to mobilize voters who want Costa Rica to ignore the ruling or withdraw from the treaty that led to their involvement in the court. However, the center-left candidate, Carlos Alvarado Quesada of the Citizen Action party, campaigned as a supporter of LGBT rights with the promise to implement the court decision once elected. In the end, Alvarado Quesada won by a margin of more than 20 points, a stunning result in a campaign focused on LGBT rights, considering the degree of opposition to same-sex marriage in this largely Catholic state.

In Mexico, a 2015 court decision has effectively made it possible for same-sex couples to wed throughout Mexico, as anyone residing in a state that has not legalized same-sex marriage can sue to get a court injunction, which must be approved (Díez, 2018). This judicial ruling helped lead toward as -yet-unsuccessful efforts to pass equal marriage legislation, and thus Mexico has not yet achieved marriage equality officially (although it has in practice) (Díez, 2018). No presidential systems achieved marriage equality nationally via referendum, although the use of a referendum was debated but not pursued in Argentina and Mexico. Nevertheless, the states of Maine, Maryland, and Washington in the United States achieved marriage equality at the state level through ballot initiatives or referendums. Additionally, voters in Minnesota rejected a ballot initiative banning same-sex marriage, which led to the speedy passage of equal marriage legislation.

Institutional contexts influence activists’ perceptions about possible pathways to the legalization of same-sex marriage and thus impact activists’ tactical repertoires, with some approaches more time-consuming or resource-intensive than others. About half of the countries that have adopted marriage equality (and indeed many of the early countries to legalize same-sex marriage) are parliamentary systems, but there are a growing number of semi-presidential and presidential systems with marriage equality. Interestingly, while the battle for marriage equality often involves a similar array of tactics (legislation, litigation, and referendums) across diverse types of political systems, legislation is a much more common means to achieving marriage equality in parliamentary and semi-presidential systems and litigation is more common in presidential systems.

Centralization and Constitutional Anti-Discrimination Protections

There is a growing body of scholarship on the impact of centralization in federal versus unitary states and the presence of inclusive constitutional anti-discrimination protections on advocacy and policymaking regarding same-sex marriage. Smith (2008) argues that Canada allows a more centralized federal role regarding lesbian and gay rights policy issues and that Canadian courts have exerted more influence than American courts in advancing LGBT rights due to an institutional structure that unifies the provincial and federal courts, especially because judges at both levels are appointed by the federal government and provinces lack freestanding constitutions or mechanisms for direct democracy, minimizing efforts to overturn court rulings. The unified jurisdiction of Canadian courts means that courts in each province have to account for one another’s decisions, contributing to a wave of litigation and pushing the federal government to create a uniform policy, particularly once court decisions citing the Canadian Charter of Rights and Freedoms pushed the government into action (Smith, 2008). In 2008, Smith suggested that although Canadian and American courts have both positively impacted LGBT rights and ruled in favor of same-sex marriage using similar claims, US courts have had less impact than Canadian courts. Jurisdiction over many lesbian and gay rights policy issues resides at the state level, and state courts in the United States are more independent and separate from the federal courts, particularly as federal judges are appointed federally while states determine selection processes for state-level judges (Smith, 2008). Further, states have used various strategies, ranging from elections of new judges to appeals, in order to challenge court rulings (Smith, 2008). Likewise, Smith (2008) highlights the importance of freestanding state constitutions, some of which incorporate more inclusive rights provisions and were used to justify state court decisions affirming lesbian and gay rights. Further, some constitutions provide states with procedures for hosting ballot initiatives or referenda through which voters are able to vote on legislation or on constitutional amendments regarding same-sex marriage (Smith, 2018). Since it was assumed that an increasingly conservative Supreme Court would rule negatively on same-sex marriage cases, activists focused on keeping legal cases out of federal courts to avoid a damaging decision that could set a long-term precedent, as occurred previously regarding sodomy (Smith, 2018). However, given the tremendous wave of affirmative court decisions citing the equal protection doctrine at the state and federal levels, American courts appear to have played an equally significant role in achieving marriage equality compared to Canadian courts, even though the decentralized American brand of federalism resulted in a more drawn-out process to achieve marriage equality.

Díez (2018) has built on Smith’s work by exploring the impact of the type of federalism as well as patterns of devolution in accounting for dynamics in marriage equality movements and policy outcomes in Argentina and Mexico. In both Argentina and Mexico, policy innovation regarding LGBT rights was promoted by constitutional reforms that devolved power to Buenos Aires and Mexico City, with activists lobbying successfully to enact non-discrimination protections and subsequently civil unions in these cities. However, institutional differences between these regimes led to divergent approaches once activists started to advocate for marriage equality. In Argentina, the country’s national civil code governs family law, which meant that activists focused on lobbying legislators in the national Congress and eventually deployed strategic litigation in federal courts, given the low level of support they encountered among legislators. After a ruling affirmed that limiting marriage to heterosexual couples is unconstitutional, activists engaged in a highly organized lobbying campaign, which contributed to the successful passage of marriage equality legislation. Although several provinces tried to pass laws allowing public officials to refuse to officiate weddings via religious exemptions, the National Anti-Discrimination Institute blocked these bills. In Argentina, the national campaign waged by activists focused on both legislation and litigation and helped to build support among both political elites and the public.

In comparison, of the federal systems in Latin America, Mexico is the only country to give subnational governments jurisdiction over marriage and other areas of family law, requiring marriage equality activists to carry on campaigns targeting each state, reflecting a decentralized fragmentation similar to the American context (Díez, 2018). Some activists focused on pursuing same-sex marriage via legislation in Mexico City, while other activists were opposed to this strategy due to concerns about backlash and favored using litigation in subnational courts to advance marriage equality, with the possibility that court rulings could eventually be appealed to the Supreme Court to achieve a national policy victory. Eventually, a same-sex marriage bill was approved in Mexico City after activists successfully lobbied city legislators, but this legislation was challenged by the federal government and several state governments in the Supreme Court. Even after rulings affirmed the constitutionality of the bill and required other states to recognize same-sex marriages carried out in Mexico City, many other states were unwilling to recognize these marriages and even changed state constitutions to define marriage as between a man and a woman. After considerable additional litigation challenging states’ discriminatory policies, the Supreme Court ruled that states’ constitutional provisions limiting marriage to heterosexual couples were unconstitutional, requiring every judge in the country to grant legal injunctions to same-sex couples if they were denied applications to marry, creating de facto marriage equality. After President Enrique Peña Nieto spearheaded an initiative to amend the Mexican Constitution and legalize same-sex marriage, efforts to pass national legislation have been stymied by the strong backlash created by opponents to marriage equality, including efforts to pass laws banning same-sex couples from adopting. As a result, the issue of marriage equality in Mexico is still far from settled. Activists are still campaigning for marriage equality and other LGBT rights issues being challenged by the opposition, despite consistent rulings by the Supreme Court affirming the constitutionality of same-sex marriage.

LGBT rights have more easily become judicialized in federal systems like Brazil, where the courts have seen it as their responsibility to become involved when legislative inaction left same-sex couples and their families in legal limbo (Valiquette & Waring, 2018). Litigation has indeed been instrumental in leading to marriage equality in federal systems like Austria, Brazil, Mexico (on a de facto basis), and the United States, although legislation has been used as a tactic in all these countries. However, Argentina, Australia, Belgium, Canada, and Germany are all federal systems that have achieved marriage equality nationally via legislation, although litigation also helped pave the way for legislation in most of these states and a plebiscite was crucial in leading to the passage of equal marriage legislation in Australia. It is noteworthy that in several of the countries with federal systems (e.g., Brazil, Canada, Mexico, and the United States), certain states, provinces, or cities were innovators that legalized same-sex marriage earlier, with policy change gradually spreading to other regions. In these countries, various means were used to legalize marriage equality at the state and provincial levels, including legislation (in Mexico and the United States), judicial rulings or decisions by government officials (in Brazil, Canada, Mexico, and the United States), and ballot initiatives or referendums (in the United States). While Australia was the only country to use a plebiscite at the national level and the United States used direct democracy at the state level, activists in several other federal systems debated holding a referendum or plebiscite.

Furthermore, the high centralization of unitary states may facilitate legislative pathways to marriage equality. The absence of state courts, subnational legislatures, and state constitutions in unitary states means that subnational regions cannot be used as incubators for policy innovation, building momentum for national change (Valiquette & Waring, 2018). Hence, it is more challenging for marriage equality activists in unitary states to use litigation in national courts as a means to achieve marriage equality (Valiquette & Waring, 2018). In fact, court decisions in countries like Chile, France, Ireland, Italy, and Portugal have illustrated judicial restraint and deference for legislative action (de Frietas & Tega, 2014; Reyniers, 2014; Tobin, 2016; Valiquette & Waring, 2018). It is noteworthy that nearly all of the unitary states that have legalized same-sex marriage have done so via legislation, although litigation was also used as a tactic in most of these states. Nevertheless, in unitary states like Colombia, South Africa, and Taiwan, litigation in domestic courts still has been crucial in delivering marriage equality, although legislation has also been used as a tactic in these cases. Activists in several unitary states called for a referendum or plebiscite. However, only Ireland used a referendum as a mechanism to help deliver marriage equality, and only Slovenia used a referendum to block same-sex marriage before marriage equality was subsequently adopted via legislation.

In addition, some states have adopted new constitutions that include protections against discrimination based on sexual orientation or gender identity, and these more inclusive constitutional protections have provided activists an avenue for using litigation to advance marriage equality. Smith (2008) argues that the recent drafting of Canada’s Charter of Rights and Freedoms, with the equality clause in Section 15 barring discrimination on various grounds, has facilitated the advancement of LGBT rights in Canada. While sexual orientation and gender identity are not included as protected categories, she argues that the clause has subsequently been interpreted as applying an equal level of scrutiny to all groups, including based on sexual orientation and gender identity (Smith, 2008). The Charter of Rights and Freedoms was quickly viewed as a part of Canadian national identity, which enabled the LGBT rights movement to frame equality as a Canadian or Charter values issue, linking LGBT rights to the human rights regime institutionalized by the Charter and to Canadian nationalism (Smith, 2018). Similarly, Mostacci (2014) suggests that one of the reasons the South African Constitutional Court was particularly empowered to rule on marriage equality was the decision by the post-apartheid government to adopt a highly modern constitution prohibiting discrimination based on sexual orientation, a decision that may have been inspired by Canada’s Charter of Rights and Freedoms.

In countries that lack constitutional protections against discrimination based on sexual orientation or in which there is no single constitutional document, it is more daunting (though not impossible) to challenge the constitutionality of laws limiting marriage to heterosexual couples. Although the Bill of Rights played an important role in the nationalization of civil rights in the United States by pushing states to come into compliance with federal standards, Smith suggests that the impact of the Bill of Rights in advancing LGBT rights via the courts has been limited (Smith, 2008). The equal protection doctrine in the Fourteenth Amendment to the US Constitution is interpreted as the constitutional floor for protections of certain rights (Smith, 2008). Stricter scrutiny is applied to government action involving certain groups, such as those differentiated by race (Smith, 2008). Smith (2008) also emphasizes how the doctrine of fundamental rights which all citizens are accorded, has shaped US litigation. Because the marginalization of citizens based on sexual orientation and gender identity was not salient to political elites at the time the Bill of Rights was drafted, these classes were left unaccounted for (Smith, 2008). In the American cultural context in which the Democratic Party was often viewed as catering to minority groups, gay rights organizers were sometimes critiqued as special interest groups seeking special rights, making it difficult for activists to make headway in arguing that sexual orientation and gender identity should be recognized as protected categories subject to higher scrutiny (Smith, 2008). It is noteworthy that the majority opinion written by Justice Kennedy in 2015 did not directly address whether heightened scrutiny should be applied to equal protection claims involving sexual orientation, but it did describe sexual orientation as immutable. Nevertheless, despite early obstacles in making rights-based arguments, Smith suggests that a discursive shift took place with American activists linking marriage equality to a legal framing of rights (Smith, 2018). Finally, in countries that lack a single document guaranteeing individual rights, litigation is not the key strategy used to achieve marriage equality. In the United Kingdom, which lacks a written constitution, most advancements regarding LGBT rights have occurred from legislation and not litigation (O’Neill, 2014). Similarly, in Australia, the absence of a single bill of rights document led activists to focus on winning marriage equality via legislation instead of via litigation (Bernstein & Naples, 2015; Johnson & Tremblay, 2016).

Venue shopping is very common in each of these political systems, as dynamics in the opportunity structure influence activists’ decisions about where to pursue litigation or legislation and when to shift from one strategy to another. American marriage equality activists fought for same-sex marriage with resource-intensive state-by-state campaigns involving litigation, legislation, and ballot initiatives or referenda, taking advantage of multiple venues to target and competing with one another to exert influence on courts, executives, and legislatures (Smith, 2018). In Argentina, activists took advantage of the liberal environment and greater political autonomy of several cities within which to pursue early litigation and legislation (Díez, 2011). The LGBT movement relied on experienced lawyers to carefully select the right judges to send cases (Andía, 2013). The momentum from favorable court rulings was subsequently used by the movement to successfully lobby allies in Congress to pass equal marriage legislation (Andía, 2013). Institutional factors shape potential litigation and court decisions and thus can create political opportunities and obstacles that adept marriage equality activists or their opponents may try to exploit (Andersen, 2005). Since Australia lacks a single bill of rights document, activists avoided using the courts and focused on other tactics (Bernstein & Naples, 2015). However, activists also encountered difficulties in lobbying legislators to pass a marriage equality bill (Bernstein & Naples, 2015). Thus, Bernstein and Naples (2015) suggest that the blocked opportunity structure at the national level in Australia contributed to a delay in developing a nationally organized campaign to support marriage equality. In Brazil, evangelical opposition to LGBT rights limited both congressional and executive support for passing marriage equality and other LGBT rights legislation, and thus activists lobbied elected officials at the subnational level while focusing on litigation at the federal level (Valiquette & Waring, 2018).

Electoral Systems, Party Systems, Parties as Movement Allies, and Conscience Votes

Some scholars have argued that the electoral system context shapes the tactics used by marriage equality activists and policymaking regarding same-sex marriage. Bernstein and Naples (2015) suggest that in states with majority/plurality or winner-take-all electoral systems in which citizens vote for candidates for legislative office instead of a political party, elected officials are able to function more independently of their party and are potentially more swayable by social movements. Australia, Canada, France, the United Kingdom, and the United States share majority/plurality electoral systems, although Australia uses ranked choice voting and France holds two rounds if no candidate wins the required number of votes. While majority/plurality electoral systems may open up avenues for lobbying candidates, voters may also more easily hold candidates accountable for their policy standpoints. The fact that Australia, Canada, France, and the United Kingdom (England, Scotland, and Wales) passed marriage equality legislation, even when elected officials could potentially be punished in subsequent elections, shows the strength of support for marriage equality among legislators and suggests that these political contexts may have been conducive to activists’ lobbying efforts. In comparison, passing marriage equality legislation was not an option in the American political context as many legislators within the Republican Party were opposed to marriage equality, and thus the Supreme Court proved a better venue to achieve marriage equality.

Mixed member proportional systems found in states like Germany, Mexico, New Zealand, and Taiwan are of interest as they allow researchers to compare legislators elected via majority/plurality versus those elected via proportional representation (PR). Rich (2017) finds that party-list legislators elected via PR were more likely to be supportive of same-sex marriage than district legislators in both of Taiwan’s main political parties. In both Mexico and Taiwan, marriage equality is the process of being actualized via court decisions. In comparison, in both Germany and New Zealand, marriage equality arrived via legislation when the government was controlled by a conservative party or coalition led by a conservative party. German members of parliament (MPs) from leftist parties such as the Social Democratic Party, the Greens, and the Left Party supported same-sex marriage regardless of how they were elected, while the conservative Christian Democratic Union/Christian Social Union was split, with less than one-third of the party’s legislators joining other MPs to legalize same-sex marriage. In New Zealand, MPs from leftist parties such as the Labour Party and the Green Party as well as from indigenous parties such as the Maori Party and the Mana Party overwhelmingly supported marriage equality, regardless of how they were elected (although it is noteworthy that the Greens had MPs exclusively selected from party lists and the indigenous parties only had district legislators). The conservative National Party was split, with under half of the party’s legislators joining other MPs to legalize same-sex marriage, and all members of the nationalist New Zealand First Party (which only included MPs selected from the party list) opposing marriage equality.

Interestingly, of all the countries that have legalized marriage equality, PR electoral systems are the most common, and in most of the countries with PR electoral systems, marriage equality was passed legislatively. However, the impact of PR electoral systems on legislative bodies’ policymaking regarding marriage equality has been undertheorized in previous research. PR systems are found in the following countries that have legalized same-sex marriage: Argentina, Austria, Belgium, Brazil, Colombia, Costa Rica, Denmark and its autonomous territory of Greenland, Finland, Iceland, Luxembourg, the Netherlands, Norway, Portugal, Slovenia, South Africa, Spain, Sweden, and Uruguay. Ireland and Malta both use a variant of PR, multi-winner ranked choice voting or single-transferable vote. Most of these countries passed marriage equality via legislation: Argentina, Belgium, Denmark and its autonomous territory of Greenland, Finland, Iceland, Ireland, Luxembourg, Malta, the Netherlands, Norway, Portugal, Slovenia, South Africa, Spain, Sweden, and Uruguay. Admittedly, in Ireland, legislation was created due to a referendum, and in South Africa, legislation was created due to a court decision. Only a few countries with PR systems passed marriage equality via a court decision: Austria, Brazil, Colombia, and Costa Rica.

In addition, party systems (which are themselves influenced by electoral systems) may impact the political context within which marriage equality movements campaign, as some party systems include more political parties, which may serve as potential movement allies. While the Democratic Party is the main party offering the marriage equality movement potential allies in the US two-party system, the Canadian multi-party system offered the marriage equality movement several types of potential allies, including the Liberal Party, Bloc Québécois, and the New Democratic Party (Smith, 2008). In the US political context, passing equal marriage legislation was an impossibility, whereas in Canada, a majority of legislators in each of these parties allied with the movement voted to support marriage equality, even though most Conservative Party legislators were opposed (Smith, 2008). Perhaps the fact that several of these parties served as strong supporters of marriage equality helped to make the issue more mainstream and enabled the parties to agree to hold a free vote, in which MPs could vote according to their conscience on the issue. Although center-left parties are more likely to include movement allies, center-right parties can also play an important role in the passage of equal marriage legislation (Hildebrandt, 2016). In some cases, cross-party support on same-sex union recognition helps to reduce the partisanship of the issue. In Ireland, the fact that all the main political parties integrated civil partnership as a goal in their party manifestos in the 2007 general elections was instrumental in achieving marriage equality (Knill & Preidel, 2015). Even though leftist parties have clearly been closer movement allies cross-nationally, securing support from across party lines has proved to be important strategy in passing legislation for marriage equality.

Several studies have found that electoral victories for leftist parties allied with the LGBT movement were instrumental in driving legislative policy change regarding marriage equality. Many countries achieved marriage equality through legislation passed by liberal governments or center-left or liberal coalitions (e.g., Belgium, Canada, France, Ireland, and the Netherlands). In both the Netherlands and Belgium, a national election loss by Christian Democratic parties served as a catalyst for the LGBT movement, as the new center-left governing coalitions created political opportunities to pass LGBT-friendly legislation (Kollman, 2017). In the Netherlands, the 1994 and 1998 elections marked the first post-war elections in which the Christian Democrats were excluded from the coalition government (Kollman, 2017). The marked shift to the left with two successive Purple cabinets including the Partij van de Arbeid, Volkspartij voor Vrijheid en Democratie, and the Democraten 66, was instrumental in shifting the opportunity structure and leading to the passage of legislation for registered partnerships and subsequently same-sex marriage (Kollman, 2017). Similarly, in Belgium, the 1999 election resulted in a coalition between the Flemish and French-speaking Liberal, Socialist, and Green parties that were eager to differentiate their platform from the Christian Democrats (Eeckhout & Paternotte, 2011). The Flemish Greens were key in placing same-sex marriage high on the policy agenda, but all the parties except the French-speaking Liberals helped shepherd the legislation through to passage (Eeckhout & Paternotte, 2011). In Uruguay, new political opportunities were created for the LGBTQ movement with the electoral victory of the leftist Frente Amplio party, as the movement closely calibrated their strategy with legislative allies committed to realizing policy change (Sempol, 2013). Sénac (2018) finds that the LGBT movement in Spain had a strong coalition with leftist political parties, whereas opposition movements had a weaker alliance with conservative political parties, which helped lead to the passage of the same-sex marriage law. Recently, the social democrats in Malta were able to regain power after 15 years in the opposition, after campaigning on a platform that included promoting LGBT rights and adopting civil unions (Harwood, 2015). Civil unions were legalized just over a year later, and after a second victory for the Maltese Labour Party in the next general election, marriage equality legislation was passed almost immediately (Harwood, 2015).

In research on legislative support for marriage equality and civil union bills, Hildebrandt (2016) finds that the strongest support was found among socialists, Green parties, far left parties, and liberals. Green parties and far left parties in particular are most supportive of marriage equality and unwilling to satisfice with civil unions. However, there are dynamics in leftist party support, as these parties have occasionally abstained or voted against civil union bills. In some countries, Christian democrats are very supportive of same-sex unions; for example, in Belgium and Luxembourg, most Christian democratic MPs voted in support of legislation even when leftist parties had just won control of the government. However, Christian democratic members of coalition governments have also blocked legislative progress in legalizing civil unions in Italy and in legalizing same-sex marriage in Austria and Germany in the past. Protestant parties and conservative parties tend to be strongly opposed to same-sex unions, and far right parties are strongly opposed to same-sex marriage and have decreased in their support for civil unions over time. Nevertheless, it is noteworthy that in France, Portugal, and Spain, countries in which same-sex union legislation was passed under governments controlled by leftist parties, there was no concerted effort to repeal these laws when conservative parties regained control of the government. In Canada, the Conservative party tried unsuccessfully to introduce a bill repealing marriage equality once they were elected into a minority government, but they have considered marriage equality settled since then.

Conscience votes on marriage equality may be key in passing legislation, particularly when conservative parties are in power. Bernstein and Naples (2015) suggest that conscience votes or free votes in which members of parliament are free from the constraints of party discipline are used in Westminster-style parliamentary systems in order to help parties avoid blame when enacting policies perceived as controversial. However, they acknowledge that conscience votes can both help and hinder marriage equality, as several conscience votes and weak party discipline previously blocked passage of equal marriage legislation in Australia (Bernstein & Naples, 2015). Nevertheless, free votes that ultimately brought marriage equality to Australia, New Zealand, and the United Kingdom actually occurred when these governments were under control of Conservative parties. Moreover, conservative prime ministers Malcolm Turnbull (Australia), John Key (New Zealand), and David Cameron (United Kingdom) served as allies in supporting the legislation and in ensuring a conscience vote. Similarly, in Germany, conservative Chancellor Angela Merkel was instrumental in ensuring a free vote leading to marriage equality, even though she personally voted against same-sex marriage. It is noteworthy that there are also states like Canada in which leftist governments held successful free votes on marriage equality legislation.

Even though having a free vote is meant to enable legislators to vote according to their conscience and not according to party lines, Plumb (2015) observes that partisanship was still the key predictor of MPs’ voting behavior regarding same-sex marriage bills passed in New Zealand and the United Kingdom. A study on party cohesiveness in free votes on civil partnership and same-sex marriage observed that center-left parties in New Zealand and the United Kingdom were very united in favor of same-sex union recognition, whereas conservative parties were more divided (Plumb, 2013, 2015). Conversely, in Australia and Canada, center-left parties were more divided, while the Australian Conservative Party coalition and the Canadian Conservative Party were unified in their opposition to same-sex marriage in early votes on marriage bills that were unsuccessful in leading to policy change (Plumb, 2013, 2015). Overall, party discipline tended to be high in center-left parties, and center-right parties were often split in their support of marriage equality, which helped yield enough supportive votes to pass legislation (Plumb, 2015). Even though conscience votes are intended to lessen party discipline, party cohesion in these votes still plays a crucial role in determining policy outcomes.

As mentioned earlier, party discipline can serve as a double-edged sword, facilitating or hindering passage of marriage equality bills. Strong party discipline makes it impossible for legislators within particular parties to deviate from the party platform on marriage equality, with the impact contingent on the party’s standpoint regarding same-sex marriage. Weak party discipline also influenced the passage of marriage equality, depending on whether a sufficient number of legislators were willing to support equal marriage legislation. For example, while the Australian Labor Party and Green Party have included growing numbers of marriage equality supporters, the Australian Labor Party took a long time to evolve and include marriage equality as part of its platform, and it has also included some conservative and religious MPs who strongly oppose marriage equality (Bernstein & Naples, 2015). Despite the fact that Australia has federal jurisdiction over marriage and allies for marriage equality even emerged within the center-right Liberal and National Parties, they delayed passing equal marriage legislation for a long time. Party discipline served as an obstacle in some attempts to pass legislation; at one point, a free vote actually enabled the Australian Labor Party to split their vote and block the passage of equal marriage legislation. The Australian case highlights how the intra-party variance in MPs’ standpoints on marriage equality and changes in these positions over time are important to account for. While the Australian government was headed by a center-right coalition between the Liberal Party and the National Party, they rejected repeated efforts to hold a conscience vote on equal marriage legislation. Instead, in fall 2017, they held a non-binding mail-in plebiscite to assess public support for legalizing same-sex marriage. The plebiscite may have been a delay tactic and a way of shifting responsibility away from the governing party in determining whether to have a free vote. Following a victory for the Yes campaign, which won over 60% of the vote, parliament passed the Marriage Act in a landslide vote, with cross-party support and only a handful of legislators voting in opposition.

Out LGBT Elected Officials, Political Allies, and Political Will

The presence of out LGBT elected officials, straight political allies, and the political will to enact change is crucial in both the legislature and executive branch, particularly in countries in which legislation or direct democracy have been used as means to achieve marriage equality. Out LGBT elected officials and political allies have played diverse roles in marriage equality movements, including helping to raise awareness, build public and elite support for same-sex marriage, file litigation to advocate for LGBT rights, develop coalitions between activists and policymakers, participate in constitutional conventions and public consultations regarding proposed legislative changes, mobilize voters and party supporters in referendum campaigns, modify party platforms and the policy agenda to be more inclusive of LGBT rights, and sponsor and shepherd through marriage equality and related LGBT rights legislation (Haider-Markel, 2010; Reynolds, 2013). In Ireland, a legal case brought by out Senator Dr. Katherine Zappone and her wife Dr. Ann Louise Gilligan sought recognition of their Canadian marriage (Tobin, 2016). This case led to the formation of Marriage Equality, an organization that helped in raising awareness and mobilizing support for same-sex marriage, but even more importantly, the media coverage of their loving relationship helped to make the issue personal to the Irish public (Healy, Sheehan, & Whelan, 2015). Other out LGBT legislators and allies in the Irish Oireachtas were members of the Irish Constitutional Convention discussing same-sex marriage, and they played an important role in personalizing the issue for other delegates (Healy, Sheehan, & Whelan, 2015). Moreover, these out legislators also helped mobilize supporters of their political parties during the Yes campaign for the Irish marriage equality referendum (Healy, Sheehan, & Whelan, 2015). In Australia, out lesbian MP Penny Wong played an important role in an intense intra-party struggle that led the Australian Labor Party to evolve, adding support of same-sex marriage to the party platform (Johnson & Tremblay, 2016). Out gay MP Tim Wilson took advantage of the final parliamentary debate on the bill legalizing same-sex marriage in Australia to propose to his partner, helping to make the issue highly personal to his fellow legislators. In countries like Iceland and Luxembourg, out lesbian and gay prime ministers have married their partners shortly after marriage equality became effective, helping to raise awareness and build public support for the issue, even after same-sex marriage was legalized.

Out LGBT elected officials often help to sponsor or co-sponsor LGBT rights legislation and sometimes will form caucuses or other coalitions with straight legislative allies (Haider-Markel, 2010). In New Zealand, out MP Louisa Wall introduced the bill that legalized same-sex marriage and worked with a cross-party working group to successfully mobilize enough legislative support to pass the bill (Carlyon & Morrow, 2014). Similarly, in Malta, the creation of a LGBT working group within the Labour Party helped to set marriage equality on the agenda (Harwood, 2015). In some cases, out legislators will avoid serving as a sponsor in order to have straight allies take on that role, especially if the seniority of political allies helps to legitimize the bill and reduce criticisms that LGBT legislators are catering to special interests (Haider-Markel, 2010). In fact, straight allies have played an important role in sponsoring and building legislative support for marriage equality bills, and female legislators, in particular, have been strong supporters of marriage equality across party lines (Plumb, 2015). For example, in Mexico City, Lol Kin Castañeda, a LGBT activist running for the city assembly on a platform advocating for marriage equality, lost the election but was able to get a progressive colleague to serve as an ally in working to build legislative support for same-sex marriage (Díez, 2018). In relatively short order, the bill was approved by the legislature and signed by the mayor, who also served as a staunch ally (Díez, 2018).

LGBT representation in politics may also contribute to policy change regarding LGBT rights, as contact helps shift other politicians’ stances on these issues. Both US President Barack Obama and British Prime Minister David Cameron talked about how their contact with LGBT people helped bring about their changed standpoints on same-sex marriage (Grube & van Acker, 2017). Similarly, German Chancellor Angela Merkel has mentioned that her changed standpoint on having a conscience vote regarding same-sex marriage was informed in part due to the transformative experience of meeting a lesbian couple who have adopted eight children. In the United States, Haider-Markel (2010) finds that there is strength in numbers, as increases in the number of out LGBT state legislators helped them to work together and exert more influence. In cross-national research exploring LGBT representation in national legislatures, Reynolds (2013) observes that Western European states had the highest share of out LGBT legislators, and several states have had lesbian or gay prime ministers. Moreover, Western European states have adopted several types of LGBT rights legislation at high rates, and many of these states were among the earliest states to adopt same-sex marriage (Reynolds, 2013). Reynolds finds that having LGBT representation increases the likelihood that states will pass LGBT rights laws and same-sex union laws (Reynolds, 2013).

The presence of executives who are allies to the marriage equality movement may also influence activism. During periods of divided government in presidential systems, the presence of executive allies may lead activists to focus more on lobbying the executive branch than the legislative branch. Smith (2008) argues that in the United States, the closed partisan environment during much of the Bush administration weakened the LGBT rights movement and other progressive causes, which faced financial and strategic obstacles in mobilizing support and were only able to exert limited influence on individual candidates. Openings may have been created in the political opportunity structure when President Obama shifted in his standpoint regarding same-sex marriage when running for reelection in 2012 (Smith, 2018). Although Democrats were able to strengthen their control of both houses of Congress in the 2008 election, Republicans regained control of the House of Representatives in 2010 and of the Senate in 2014. Thus, while the partisan environment for the marriage equality movement shifted favorably at the executive level, there was soon a negative shift in the partisan environment at the legislative level. Due to the separation of powers and extended periods of divided government, passing federal legislation for same-sex marriage was not feasible, and thus during the Obama administration the executive branch was a more important target than the legislative branch (Smith, 2018). As Smith (2018) predicted, the difficulties in targeting the legislature at the federal level drove activists to adopt a state-by-state approach including varied tactics (legislation, litigation, and direct democracy), followed by litigation appealed to the US Supreme Court. However, the positive environment at the executive level may have been instrumental in leading the movement to focus on lobbying the Obama administration and contributed to movement success, for example when the Obama administration instructed the Justice Department to withdraw federal opposition in legal cases challenging the constitutionality of DOMA (Smith, 2018).

Elected officials’ political will is reflected in how they exercise the power to make decisions about the inclusion of marriage equality in party platforms, playing a supportive or oppositional role in litigation regarding same-sex marriage, allowing debate or a conscience vote on a marriage equality bill, supporting legislation to repeal or replace same-sex marriage, or endorsing a referendum on the issue of same-sex marriage (Johnson & Tremblay, 2016). Johnson and Tremblay (2016) argue that political will helps to account for why Canada was a policy pioneer and Australia a latecomer regarding same-sex marriage. The Canadian legislature and executive manifested the political will to enact marriage equality, making key decisions that reflected their commitment and motivations, whereas Australian politicians lacked political will and made decisions to avoid or delay policy change, despite long-standing public support for marriage equality (Carson, Ratcliff, & Dufresne, 2018; Johnson & Tremblay, 2016). Political will to enact LGBT rights policy change can increase or decrease over time. In Malta, the Labour Party’s LGBT group and a network of domestic and transnational activists were able to convince party members that LGBT rights promotion was an integral part of the state’s commitment to human rights via their membership in the European Union, resulting in a positive change in the political will to enact policy change (Harwood, 2015). However, after the Brazilian court ruling legalized same-sex marriage, evangelical pressure in Congress led President Dilma Rouseff to lose political will, taking executive action and vetoing a bill to provide anti-homophobia toolkits to schools (Valiquette & Waring, 2018).

Use of Narratives and Frames to Make Marriage Equality Personal

The messaging of marriage equality campaigns has become increasingly reliant on narratives and frames that help make marriage equality personal (Olsen, 2014). Storytelling has been used as a strategy to enable messengers such as LGBT people and allies to share their personal journeys in coming out about their identities and the reasons behind their support for marriage equality. Frames have been used in these narratives that help to personalize the issue further, such as accentuating same-sex couples’ love and commitment to one another. Personalized messaging has been crucial in grassroots campaigns used to mobilize public support for marriage equality, particularly in direct democracy campaigns focused on mobilizing voters. Direct democracy advocacy campaigns require marriage equality activists, elected officials, and political parties to play an important role in mobilizing voters and in shifting public opinion (Healy, Sheehan, & Whelan, 2015). In the United States, ballot initiatives or referenda were used in several states as a pathway to marriage equality. Subsequently, Ireland used a referendum and Australia used a plebiscite to achieve marriage equality at the national level, although in both cases the popular vote was followed by the passage of equal marriage legislation.

In the United States, the marriage equality movement wanted to learn from mistakes made in earlier unsuccessful campaigns regarding same-sex marriage bans. Previously, campaigns adopted a strategically closeted approach to messaging in which LGBT people and their families were not very visible as messengers and frames focused around the rights and benefits sought by same-sex couples and not their loving relationships (Solomon & Patrick, 2014; Stone, 2012). Focus group research was used to develop an alternate approach to messaging in the American direct democracy campaigns, which focused on the love and commitment motivating same-sex couples to marry, the freedom to marry, and treating others as you wish to be treated—the Golden Rule (Solomon & Patrick, 2014). Interestingly, President Obama used similar language in explaining his evolved standpoint on the issue of same-sex marriage (Solomon & Patrick, 2014). Although LGBT people and their families helped to personalize the issue of same-sex marriage, straight allies who could talk about how their contact with LGBT people contributed to their support of marriage equality were particularly effective messengers in the 2012 direct democracy campaigns in Maine, Minnesota, and Washington (Solomon & Patrick, 2014). A massive grassroots voter mobilization effort was launched, including phone banks and door-to-door canvassing in which people shared their stories, tried to connect with their audience, and engaged with people non-judgmentally regardless of their viewpoints on same-sex marriage (Solomon & Patrick, 2014). President Obama’s re-election campaign was even willing to issue statements targeting each of the states with ballot initiative and referenda campaigns, urging voters to support marriage equality (Solomon & Patrick, 2014). These direct democracy advocacy campaigns were ultimately successful in yielding electoral victories for the movement (Solomon & Patrick, 2014).

Drawing on input from the American marriage equality movement, Irish activists devised a similar get-out-the-vote campaign to mobilize voters for the referendum (Healy, Sheehan, & Whelan, 2015). Out LGBT people and their families again played a central role in social media advertisements, televised referendum debates, and lobbying of elected officials. However, a diverse grouping of straight allies, whom the public could relate with and who talked about their personal journeys on the issue of same-sex marriage, were also important messengers. Sharing personal stories helped to make same-sex couples and their loving relationships tangible and relatable to the public. Marriage equality supporters used family values frames to show how marriage helps to protect same-sex couples and their families. Also, similar language was used regarding the freedom to marry and the pursuit of equality. The campaign worked hard to maintain an upbeat tone, and by using a family values frame they were able to coopt the language used by opponents. Finally, a massive grassroots effort was undertaken to register and canvas Irish voters, which was successful in yielding a high voter turnout and an electoral victory for the Yes campaign.

Harrison and Michelson (2017) conducted experiments to assess the efficacy of activists’ approaches in bringing about positive attitude change. Although the role of out LGBT people sharing their personal narratives has been key in many marriage equality campaigns, participants who were exposed to a treatment script involving a LGBT person sharing a coming out story were less likely to donate to a movement organization, suggesting that LGBT messengers may not always be as effective. However, they find that appeals which involve priming in-group identities that are unrelated to LGBT rights can in some cases be particularly effective. For example, sports fans who received a prompt about an athlete’s support for same-sex marriage or non-discrimination were more likely to be supportive of those issues. This research highlights the importance of using messengers whom participants can relate to and selecting frames that help to prime common identities. This is a practice that has been applied in a lot of the advertising created for direct democracy campaigns in which a diverse set of messengers have been selected and messages have been framed in a way that helps the public feel a sense of connection to the messenger.

Public opinion in support of same-sex marriage has grown tremendously in countries that have experienced marriage equality campaigns. For example, from 1996 to 2015, public support of same-sex marriage in the United States increased from 27% to 60% (Harrison & Michelson, 2017). Such shifting attitudes beneficially impact litigation, legislation, or direct democracy, which are used as means to achieve marriage equality. Sometimes, legislators have cited concerns about public opinion backlash to justify their reluctance to change their standpoint regarding same-sex marriage. However, research conducted in the United States suggests that the legalization of same-sex marriage has not resulted in a reduction in public support for marriage equality (Bishin, Hayes, Incantalupo, & Smith, 2016). Moreover, scholars have observed a reduction in prejudice toward homosexuality following the legalization of same-sex marriage in the United States as well as in European countries (Flores & Barclay, 2016; Hooghe & Meeusen, 2013).

Framing Marriage Equality as a Human Rights Norm

Linking LGBT rights issues such as marriage equality to human rights norms has been an important element of the discourse of transnational activists and the diffusion of marriage equality. Social learning by transnationally networked activists and policy elites may have contributed to the diffusion of arguments regarding same-sex unions, the dissemination of an international norm regarding same-sex union recognition, and thus the convergence of policymaking (Kollman, 2007, 2013; Paternotte, 2015). Although domestic causal factors may be more salient in states that were among the first wave of policy pioneers legalizing same-sex unions, Kollman (2013) suggests that international norms become more significant causal influences among the next wave of policy adopters. International norm diffusion is particularly relevant in Europe because the increasing integration of supranational institutions with Europeanization has provided structured opportunities for transnational networks of activists and policy elites to interact and internalize international norms, leading to policy convergence when states apply lessons learned abroad and decide to harmonize domestic policies (Paternotte & Kollman, 2013). Indeed, many of the first countries to legalize same-sex marriage have been Western European states that are members of the European Union; however, there are also Western European states that have been reluctant or unwilling to legalize marriage equality, and with the exception of Slovenia, Eastern European states have been unwilling to embrace marriage equality. Although the European Court of Human Rights has not yet interpreted the right to marry to include same-sex couples, one ruling may have contributed to Austria’s legalization of registered partnerships, setting the stage for later litigation regarding same-sex marriage (Pustorino, 2014). More recently, the ruling by the Inter-American Court of Human Rights illustrates the significant impact supranational court decisions may eventually have on marriage equality policy diffusion, particularly in states reluctant to embrace change.

Although the transnational diffusion of rhetoric and norms regarding same-sex unions impacts advocates’ framing of marriage equality as a human rights issue, Kollman (2013) acknowledges that domestic activists also customize their framing of grievances in response to the national context, which may contribute to cross-national variation in policy outcomes. For example, although European frames were used to advocate for same-sex unions in Germany, activists failed to differentiate between registered partnerships and marriage and prioritized the former, and thus policymakers moved forward on registered partnerships in 2001 but delayed legalizing same-sex marriage (Kollman, 2013). Similarly, dynamics in the role of religion and perceptions about the legitimacy of international norms impact the ways in which norms are interpreted and same-sex union policies are adopted (Kollman, 2007, 2013). President Obama’s shifted standpoint on same-sex marriage may also have put pressure on political elites and activists in other states to embrace marriage equality as a human rights issue, seeking to keep up their previous track record on LGBT rights (Ayoub, 2015). However, recent efforts by Western democracies like the United States to promote LGBT rights as human rights in other parts of the world have been received with mixed responses (Encarnación, 2014).

The link between LGBT rights and human rights, especially in democracies, has shifted the ways in which advocates frame marriage equality (Encarnación, 2014). In Spain, the legalization of same-sex marriage was framed as part of the ongoing efforts to improve gender equality policies and the quality of democracy (Sénac, 2018). In Mexico and Argentina, same-sex marriage was framed as a human rights issue, linked to democracy and equality (Díez, 2018). Arguments for same-sex marriage that tie marriage equality to human rights and democracy help to build public support for same-sex marriage. Dion and Díez (2017) observe that supporting democracy and democratic values increases support for same-sex marriage in Latin America, using cross-national survey data. Thus far, marriage equality has primarily been achieved in democracies in which LGBT rights are becoming internalized as human rights. However, in some of these countries, a patchwork of LGBT rights policy change has occurred, and other types of LGBT policy change regarding non-discrimination, parenting, hate crimes, or gender recognition may lag behind. Marriage is a conservative institution and may be more palatable to some domestic audiences than other, more progressive LGBT rights issues.

Using Family Values Frames to Coopt Opponents’ Messaging

Marriage equality supporters have used frames focused on family values to respond to religious opponents’ usage of counterframes focused on children’s well-being. The dynamics of movement and countermovement mobilization may also influence countries’ policymaking regarding same-sex marriage. In countries with religious cleavages, legislative support for marriage equality bills is lower among parties of both the right and the left (Hildebrandt, 2016). Marriage equality legislation has passed in Argentina, France, and Ireland, despite strong Catholic and Evangelical opposition (Encarnación, 2013; Knill & Preidel, 2015; Sénac, 2018). However, changing attitudes toward religion and the church as well as the presence of religious dissenters who supported marriage equality may have impacted the role of religious opposition in different contexts (Encarnación, 2013; Sénac, 2018). Knill and Preidel (2015) explore why Ireland is a highly religious, predominantly Catholic state that has legalized same-sex marriage, while Italy has been unable to pass same-sex marriage legislation. In Ireland, the Catholic Church was a passive participant in the campaigns opposing marriage equality, refraining from giving many political statements, while LGBT interest groups were given greater access and input in the referendum campaign and policymaking process (Knill & Preidel, 2015). Further, some Catholic advocates played an important role in supporting marriage equality during the Irish referendum campaign (Winter, 2018). However, Knill and Preidel (2015) argue that the reason the Catholic Church exerted greater political veto power and helped block marriage equality in Italy stems from active church lobbying in a highly fragmented, unstable political system which facilitates access for Catholic lobbyists. Similarly, the role of Evangelical, Catholic, or Orthodox churches in certain Eastern European and Latin American countries has contributed to reluctance by legislators to pass laws enabling states to come into compliance with domestic or supranational court decisions regarding marriage equality and other LGBT rights (Bodnar & Śledzińska-Simon, 2014; Valiquette & Waring, 2018).

Countermovement mobilization has blocked marriage equality in some countries and limited the passage of LGBT rights legislation elsewhere. Counterframes used by American opposition movements often focus on same-sex marriage as a threat to children’s well-being (Olsen, 2014). In Mexico, strong opposition movements have made it impossible to pass marriage equality legislation, even after consistent Supreme Court rulings affirming the constitutionality of same-sex marriage, and have even led to backlash regarding same-sex adoption (Díez, 2018). In France, strong opposition movements contributed to the delay in achieving marriage equality and also drove backlash as opponents worked to challenge same-sex parenting rights and the questioning of gender roles (Sénac, 2018). Amidst heated protests and virulent rhetoric from the opposition about harm to children, France ended up legalizing same-sex marriage as well as same-sex adoption, but waiting for several more years to address key family rights issues such as access to fertility treatments or parental recognition in cases of foreign surrogacy (Sénac, 2018).

Countermovement mobilization may have helped to put marriage equality on the agenda of the American LGBT rights movement (Dorf & Tarrow, 2014). Moreover, marriage equality supporters in the United States came to embrace family values frames, making arguments about how children benefit when the loving relationships between LGBT parents and their families are recognized, arguments intended to coopt their opponents’ messaging (Olsen, 2014). Similarly, Irish activists sought to coopt opponents by adopting family values frames that had been used so detrimentally in past anti-LGBT rights campaigns (Healy, Sheehan, & Whelan, 2015). They sought to avoid repeating the mistakes observed in countries like France by working with politicians to pass a separate bill that addressed same-sex parenting and other family law issues, right before the referendum on marriage equality, so that the referendum remained focused on same-sex marriage and not on children’s well-being (Tobin, 2016). In addition to using family values frames, marriage equality campaigns have also become extremely reliant on storytelling by LGBT families and their children, whose personal narratives help to make these issues tangible (Olsen, 2014).

Homonationalist Versus Homophobic Discourses

While some politicians and activists have adopted homonationalist discourses to argue in favor of marriage equality, other actors have used homophobic rhetoric to oppose marriage equality as well as other LGBT rights issues. To begin, mechanisms such as social learning and policy imitation may have facilitated marriage equality policy diffusion, leading the earliest adopters of marriage equality to become policy pioneers and subsequently leading other states or subnational regions to join in becoming policy innovators. Policymakers study the outcomes and effects of policy change in other jurisdictions and use this information when considering policy adoption, and they may adopt policies that neighboring regions have implemented in order to continue being perceived as attractive (Mitchell & Petray, 2016). Marriage equality campaigners may have worked to build support for such policy change by linking policy innovation around same-sex marriage to core values and national identity. Early-adopter countries like the Netherlands and states like Massachusetts embraced their roles as policy pioneers (Kollman, 2017; Mitchell & Petray, 2016). In the Netherlands, homonationalism was used to develop support for marriage equality by linking Dutch national identity, tolerance of homosexuality, and pride in being a policy pioneer with the promotion of LGBT rights and marriage equality policy diffusion (Kollman, 2017). Similarly, in Ireland, activists linked marriage equality to embracing a more progressive Irish national identity that values diversity and equality and moves away from a past in which Ireland was known for being a reluctant latecomer in policy diffusion regarding LGBT rights issues like decriminalization (Healy, Sheehan, & Whelan, 2015). As the number of countries with marriage equality have increased, there is more pressure on other countries not to fall behind and to amend their policies to be on the right side of history (Healy, Sheehan, & Whelan, 2015).

However, the legalization of same-sex marriage may have inspired a backlash to LGBT rights and marriage equality. State homophobia and religious opposition may have led certain countries or subnational regions to become policy defectors, limiting or repealing existing LGBT rights policies including same-sex marriage or adopting new policies detrimental to LGBT rights. Increasingly global homophobic discourses by politicians have emerged in which states promoting LGBT rights and marriage equality are framed as cultural imperialists threatening national identities, traditional values, gender roles, and the family as an institution (Currier & Moreau, 2018; McKay & Angotti, 2016). Backlash may lead certain states to enact policies detrimental to LGBT rights, like religious freedom exemptions enabling discrimination of married same-sex couples or even repealing same-sex marriages. In the United States, the legalization of same-sex marriage in Massachusetts was initially followed in other states by a rapid increase in marriage definition amendments that limited marriage to one man and one woman, although there was a slowing of these amendments when same-sex marriage began to be legalized in more states (Mitchell & Petray, 2016). After many European Union member states legalized same-sex marriage or civil unions, Hungary approved a new constitution that limited marriage to heterosexual couples and prioritized protecting the traditional family as an institution while denying same-sex families legal protections (Bodnar & Śledzińska-Simon, 2014). After England, Scotland, and Wales legalized same-sex marriage, Bermuda, which is a British territory, legalized same-sex marriage via a 2017 Supreme Court decision, only to pass a bill repealing and replacing same-sex marriage with domestic partnerships in 2018. It is entirely plausible that other countries may backtrack on marriage equality or enact policies to weaken the protections of marriage, particularly if unpopular court decisions are the pathway by which same-sex marriage arrives.

Conclusion

With same-sex marriage legalized in over two dozen countries in less than two decades, the rapid pace of marriage equality policy diffusion is an exciting development for LGBT rights and bodes well for marriage equality campaigns pursuing policy change in non-adopter states. The geographic scope of policy convergence, with same-sex marriage making considerable inroads in North America, South America, and Western Europe as well as several states in other regions, suggests that marriage equality and LGBT rights are becoming internalized as human rights norms transnationally. However, policy diffusion has been limited in Eastern Europe, the Middle East, Africa, and Asia. Understanding how institutional and cultural factors have impacted activists’ strategies and messaging in states that have legalized same-sex marriage may help in understanding how these factors impact marriage equality movements and policy change in other states. However, these causal influences may operate differently or be superseded by other types of institutional and cultural factors in other national contexts.

States have followed divergent trajectories in pursuing LGBT rights policies, and it is important to assess the relationship between policymaking regarding related LGBT rights issues and policymaking regarding same-sex marriage. Sometimes interventions like domestic or supranational court decisions lead states to bypass certain policy changes like the passage of non-discrimination laws. The incremental approach to policy change may not generalize well to certain world regions, where marriage equality is not a top priority compared to other LGBT rights issues and may in fact drive policy backlash regarding those issues. Further, parliamentary, semi-presidential, and presidential systems provide different opportunity structures which marriage equality activists must navigate, influencing their strategic choices. However, the success in achieving marriage equality across varied institutional contexts, as well as the diverse tactics used within each type of political system, accentuate the importance of examining the influence of other causal factors. Moving forward, as marriage equality campaigns gain traction in non-democratic political contexts, the unique institutional and cultural factors in these regimes need to be explored. The level of centralization in federal versus unitary states and the presence of inclusive constitutional protections against discrimination also influence the tactics activists have used in the battle for marriage equality and must be attended to. More research is needed on the effect of electoral systems and party systems on marriage equality policymaking. There is considerable variation in parties’ standpoints concerning same-sex marriage and other LGBT rights issues among parties of both the left and the right, which may have influenced party-movement alliances. Subsequent research also needs to examine the utility of conscience votes, depending on which party is in power, as well as the role of party discipline. The role of out LGBT elected officials and straight political allies, LGBT and youth party groups, cross-party working groups, and LGBT caucuses and the political will to enact change are also essential, especially when legislation or direct democracy are used as means to achieve marriage equality.

In addition, the cultural context within which movements operate influences their messaging and how they frame movement grievances. One common approach that has spread transnationally has involved using narratives and frames that make issues like same-sex marriage personal. Further, the diffusion of LGBT rights as human rights norms, the spread of discourse linking these issues, and activists’ growing embrace of frames that link marriage equality and human rights may also have contributed to marriage equality policy diffusion. Marriage equality campaigns have embraced family values frames as a means to coopt opposition movement counterarguments regarding children’s well-being. Although movement-countermovement dynamics are important to investigate domestically, it is also important to attend to the ways in which marriage equality activists learn lessons by studying movement-countermovement dynamics in other countries. As marriage equality movements drive forth policy convergence in other world regions, it is important to gauge the ways in which activists adjust their messaging in response to additional cultural factors. Homonationalist discourses linking national identity, tolerance of homosexuality, and adoption of marriage equality may have resonated well in states in which LGBT rights have been internalized as human rights norms. Homophobic discourses have been used to oppose LGBT rights in countries that have enacted discriminatory policies or that lack legal protections for LGBT people, but they have also been used to advocate for policy reversal in countries that have previously embraced marriage equality and other LGBT rights policies (Bosia, 2013). Hence, the role of nationalist and far right movements and parties in promoting policy backlash by linking homophobia with Islamophobia, xenophobia, and racism is a serious concern that merits further investigation globally.

The existing scholarship on marriage equality policy diffusion has been particularly reliant on single or comparative case studies that hone in on certain causal factors operating in each country at a particular moment in time. This article contributes to this research by examining how institutional and cultural factors perform in accounting for the dynamics in marriage equality activism and policy diffusion across a broad range of national contexts. In addition to providing a comprehensive account of state-of-the-art research concerning all of the states that have legalized same-sex marriage, a detailed analysis of the tactics used to achieve policy change is presented to illustrate the strengths and limitations of institutional arguments in accounting for dynamics in policy diffusion. Qualitative case studies are invaluable in exploring how causal mechanisms influence activists’ tactics and messaging as well as policy diffusion. However, additional large-n cross-national and experimental research is needed to test competing hypotheses and examine the generalizability of causal factors across diverse national contexts.

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