Law and Economics

Administrative law refers to the body of legal doctrines, procedures, and practices that govern the operation of the myriad regulatory bodies and other administrative agencies that interact directly with individuals and businesses to shape economic and social outcomes. This law takes many forms in different legal systems around the world, but even different systems of administrative law share a focus on three major issues: the formal structures of administrative agencies; the procedures that these agencies must follow to make regulations, grant licenses, or pursue other actions; and the doctrines governing judicial review of administrative decisions. In addressing these issues, administrative law is intended to combat conditions of interest group capture and help ensure agencies make decisions that promote the public welfare by making government fair, accurate, and rational.

“Antitrust” or “competition law,” a set of policies now existing in most market economies, largely consists of two or three specific rules applied in more or less the same way in most nations. It prohibits (1) multilateral agreements, (2) unilateral conduct, and (3) mergers or acquisitions, whenever any of them are judged to interfere unduly with the functioning of healthy markets. Most jurisdictions now apply or purport to apply these rules in the service of some notion of economic “efficiency,” more or less as defined in contemporary microeconomic theory. The law has ancient roots, however, and over time it has varied a great deal in its details. Moreover, even as to its modern form, the policy and its goals remain controversial. In some sense most modern controversy arises from or is in reaction to the major intellectual reconceptualization of the law and its purposes that began in the 1960s. Specifically, academic critics in the United States urged revision of the law’s goals, such that it should serve only a narrowly defined microeconomic goal of allocational efficiency, whereas it had traditionally also sought to prevent accumulation of political power and to protect small firms, entrepreneurs, and individual liberty. While those critics enjoyed significant success in the United States, and to a somewhat lesser degree in Europe and elsewhere, the results remain contested. Specific disputes continue over the law’s general purpose, whether it poses net benefits, how a series of specific doctrines should be fashioned, how it should be enforced, and whether it really is appropriate for developing and small-market economies.

In the wake of the 2008 financial collapse, clearinghouses have emerged as critical players in the implementation of the post-crisis regulatory reform agenda. Recognizing serious shortcomings in the design of the over-the-counter derivatives market for swaps, regulators are now relying on clearinghouses to cure these deficiencies by taking on a central role in mitigating the risks of these instruments. Rather than leave trading firms to manage the risks of transacting in swaps privately, as was largely the case prior to 2008, post-crisis regulation requires that clearinghouses assume responsibility for ensuring that trades are properly settled, reported to authorities, and supported by strong cushions of protective collateral. With clearinghouses effectively guaranteeing that the terms of a trade will be honored—even if one of the trading parties cannot perform—the market can operate with reduced levels of counterparty risk, opacity, and the threat of systemic collapse brought on by recklessness and over-complexity. But despite their obvious benefit for regulators, clearinghouses also pose risks of their own. First, given their deepening significance for market stability, ensuring that clearinghouses themselves operate safely represents a matter of the highest policy priority. Yet overseeing clearinghouses is far from easy and understanding what works best to undergird their safe operation can be a contentious and uncertain matter. U.S. and EU authorities, for example, have diverged in important ways on what rules should apply to the workings of international clearinghouses. Secondly, clearinghouse oversight is critical because these institutions now warehouse enormous levels of counterparty risk. By promising counterparties across the market that their trades will settle as agreed, even if one or the other firm goes bust, clearinghouses assume almost inconceivably large and complicated risks within their institutions. For swaps in particular—whose obligations can last for months, or even years—the scale of these risks can be far more extensive than that entailed in a one-off sale or a stock or bond. In this way, commentators note that by becoming the go-to bulwark against risk-taking and its spread in the financial system, clearinghouses have themselves become the too-big-to-fail institution par excellence.

A patent is a legal right to exclude granted by the state to the inventor of a novel and useful invention. Much legal ink has been spilled on the meaning of these terms. “Novel” means that the invention has not been anticipated in the art prior to its creation by the inventor. “Useful” means that the invention has a practical application. The words “inventor” and “invention” are also legal terms of art. An invention is a work that advances a particular field, moving practitioners forward not simply through accretions of knowledge but through concrete implementations. An inventor is someone who contributes to an invention either as an individual or as part of a team. The exclusive right, finally, is not granted gratuitously. The inventor must apply and go through a review process for the invention. Furthermore, a price for the patent being granted is full, clear disclosure by the inventor of how to practice the invention. The public can use this disclosure once the patent expires or through a license during the duration of the patent. These institutional details are common features of all patent systems. What is interesting is the economic justification for patents. As a property right, a patent resolves certain externality problems that arise in markets for knowledge. The establishment of property rights allows for trade in the invention and the dissemination of knowledge. However, the economic case for property rights is made complex because of the institutional need to apply for a patent. While in theory, patent grants could be automatic, inventions must meet certain standards for the grant to be justified. These procedural hurdles create possibilities for gamesmanship in how property rights are allocated. Furthermore, even if granted correctly, property rights can become murky because of the problems of enforcement through litigation. Courts must determine when an invention has been used, made, or sold without permission by a third party in violation of the rights of the patent owner. This legal process can lead to gamesmanship as patent owners try to force settlements from alleged infringers. Meanwhile, third parties may act opportunistically to take advantage of the uncertain boundaries of patent rights and engage in undetectable infringement. Exacerbating these tendencies are the difficulties in determining damages and the possibility of injunctive relief. Some caution against these criticisms through the observation that most patents are not enforced. In fact, most granted patents turn out to be worthless, when gauged in commercial value. But worthless patents still have potential litigation value. While a patent owner might view a worthless patent as a sunk cost, there is incentive to recoup investment through the sale of worthless patents to parties willing to assume the risk of litigation. Hence the phenomenon of “trolling,” or the rise of non-practicing entities, troubles the patent landscape. This phenomenon gives rise to concerns with the anticompetitive uses of patents, demonstrating the need for some limitations on patent enforcement. With all the policy concerns arising from patents, it is no surprise that patent law has been ripe for reform. Economic analysis can inform these reform efforts by identifying ways in which patents fail to create a vibrant market for inventions. Appreciation of the political economy of patents invites a rich academic and policy debate over the direction of patent law.

Corporate governance includes legal, contractual, and market mechanisms that structure decision-making within business corporations. Most attention has focused on corporate governance in large U.S. public corporations with dispersed shareholding. The separation of ownership from control in those corporations creates a unique problem, as shareholders typically have weak individual incentive to monitor managers. Mechanisms that have been developed to address this agency problem include independent directors, fiduciary duty, securities law disclosure, executive compensation, various professional gatekeepers, the market for corporate control, and shareholder activism. In most countries outside the United States, there are few companies with dispersed shareholding. Instead, most companies have a controlling shareholder or group. These companies face a different agency problem, the possibility that controlling shareholders may use their power to gain at the expense of minority shareholders. Enterprise governance refers to mechanisms aimed at related agency problems that occur in closely held companies without publicly traded equity interests. Here too the agency problem typically encountered is the potential conflict between controllers and minority investors, with the added twist that share illiquidity removes an important protection for the minority. Closely held companies have adopted a variety of contractual mechanisms to address these concerns. Other than the important but special cases of venture capital and private equity fund investments, there is less empirical evidence on governance in closely held companies because information is generally much harder to find.

A large body of work has examined the impact of corporate takeovers on the financial stakeholders (shareholders and bondholders) of the merging firms. Since the late 2000s, empirical research has increasingly highlighted the crucial role played by the non-financial stakeholders (labor, suppliers, customers, government, and communities) in these transactions. It is, therefore, important to understand the interplay between corporate takeovers and the non-financial stakeholders of the firm. Financial economists have long viewed the firm as a nexus of contracts between various stakeholders connected to the firm. Corporate takeovers not only play an important role in redefining the broad boundaries of the firm but also result in major changes to corporate ownership and structure. In the process, takeovers can significantly alter the contractual relationships with non-financial stakeholders. Because the firm’s relationships with these stakeholders are governed by implicit and explicit contracts, circumstances can arise that allow acquiring firms to fully or partially abrogate these contracts and extract rents from non-financial stakeholders after deal completion. In contrast, non-financial stakeholders can also potentially benefit from a takeover if they get to share in any efficiency gains that are generated in the deal. Given this framework, the ex-ante importance of these contractual relationships can have a bearing on the efficacy of takeovers. The ability to alter contractual relationships ex post can affect the propensity of a takeover and merging firms’ shareholders and, in turn, impact non-financial stakeholders. Non-financial stakeholders will be more vested in post-takeover success if they can trust the acquiring firm to not take actions that are detrimental to them. The big picture that emerges from the surveyed literature is that non-financial stakeholder considerations affect takeover decisions and post-takeover outcomes. Moreover, takeovers also have an impact on non-financial stakeholders. The directions of all these effects, however, depend on the economic environment in which the merging firms operate.

Historically, social observers have repeatedly noted a correlation between education and crime, observing that individuals with lower levels of education are more likely to commit crime. However, the relationship between education and crime is complex, and it is important to clearly establish causality to determine if investing in education can effectively reduce crime. Merely observing persistent educational-attainment inequalities between offenders and non-offenders is not sufficient to make any causal claims about the underlying relationship between education and crime. Many other factors can influence an individual’s decision to stay in school or commit a crime, and these factors need to be accounted for when estimating the relationship between education and crime. Economists theoretically predicted in the late 1960s that education, via its positive effect on future earnings, would reduce the probability of criminal participation. Empirical studies have since used various econometric methods to establish that, on average, education has a strong causal crime-reducing effect. One strand of this literature has established in various contexts that individuals from cohorts forced by law to stay longer in school were much less likely to end up in court or prison. There is, however, still much to be discovered about the effect of education on crime, such as the underlying mechanisms related to income or non-cognitive effects, and heterogeneities by context, education level and quality, and individual characteristics. Overall, economists widely agree that investing in education is an efficient public-spending strategy to effectively reduce crime.

In the Middle Ages, the Middle East was an economically advanced region. Driving its successes were an essentially uniform legal system that supported intra- and interregional commerce, partnership rules that supported commerce among nonrelatives, and a form of trust known as waqf, which served as both a wealth shelter and a vehicle for endowing social services with protections against state predation. These same institutions disincentivized the institutional advances needed to generate the modern economy’s infrastructure indigenously. Home-grown innovations, such as the tradable equity known as gedik and a form of waqf used for moneylending (cash waqf), were ill-suited to large-scale and perpetual enterprises. Partnerships used to form small and ephemeral enterprises did not spawn organizational forms conducive to pooling resources on a large scale and perpetually. The waqf’s rigidities led to increasingly serious capital misallocation and misuse with changes in relative prices and the emergence of new technologies. Thus, the Middle East reached the Industrial Era institutionally unprepared. Sensing an existential threat from the West, its ruling elites launched massive economic reforms in the 1800s. These reforms involved transplanting Western economic institutions to the West in a hurry. Although the Middle East’s economic performance improved greatly in absolute terms, it remained underdeveloped in 1914, and the catch-up process has continued. Until the 1700s, the economic fortunes of the Middle East’s religious minorities generally tracked those of its Muslims. Thereafter, non-Muslims pulled ahead. As the global economy modernized, they benefited from a right that, from the early years of Islam, was denied to Muslims: choice of law. With the development of modern economic institutions by Europeans, choice of law enabled non-Muslims to increase the efficiency of their business operations. In the century preceding the Industrial Revolution, non-Muslims benefited also from international treaties that strengthened their property rights vis-à-vis those of Muslims.

Economists increasingly connect legal changes to behavioral responses that many family law experts fail to see. Incentives matter in families, which respond to changes in legal regulation. Changing incentive structures linked to family law have largely affected marriage, cohabitation, and divorce. Economic analysis has been applied to assess the causes of falling marriage rates and delays in marriage. Much analysis has focused on increases in divorce rates, which appear to respond to legal changes making divorce easier, and to different settlement regimes. Less work has been done in relation to children but some research does exist showing how children are impacted by changes in incentives affecting adults.

The economic literature on abortion policy broadly is broad, studying abortion reforms that have occurred over the past two centuries, with a concentration of studies examining policy reform over the 20th and 21st centuries. The literature has examined a range of policies: both those which restrict access and those which legalize elective abortion; but within these two broad classes, the precise nature of policy reform can vary greatly. Policy reforms studied range from specific types of limits or financial barriers restricting access for particular age groups to policies which entirely criminalize or legalize elective abortion. Policies have been studied that restrict or relax individual access as well as impose regulations on abortion providers. The economic literature on abortion reform has illuminated a number of clear links, showing that increased availability of abortion decreases rates of unintended births, and vice versa when access to abortion is limited. These effects have been shown to have downstream impacts in many domains such as family formation, educational attainment, and labor market attachment, as well as impacts on health, empowerment, and broader measures of well-being such as life satisfaction and exposure to intimate partner violence. There is mixed evidence when examining the impact that abortion reform has on cohorts of children exposed to reform variation. Across contexts abortion reforms have been shown to affect the composition of cohorts of children via differential rates of access to abortion, though this compositional effect is context-dependent, and as such a number of different patterns have been documented. Compositional effects of policies often also have been shown to have a geographic component, given that certain types of individuals are more easily able to travel to access abortion where restrictions are in place in one area but not in another. Much of what is known in the economic literature on abortion is gleaned from country-level case studies and cohort variation in access, with this evidence generated from a relatively small number of countries in which reforms have occurred and data is available. In general, much of the literature available covers low fertility and industrialized settings. Additional evidence from other settings would allow for a broader understanding of how abortion reform affects well-being.

Without copyright law, authors would be unable to internalize the benefits of their writings. Copyright law reacts to this by providing authors with a period of exclusivity. The relevant legislation has a contract-like character; authors receive a period of exclusivity, and the public benefits by virtue of original writings that eventually pass into the public domain. Ideally each contract between the public and an author would be individually negotiated. Because U.S. copyright law is strictly utilitarian, authors would be “paid” the lowest amount possible to bring their works into existence. For example, popular authors may be able to internalize sufficient returns in just a few years. In other cases, a longer period of exclusivity is necessary. Huge transaction costs prohibit individual transactions and, at this writing, most works are protected for the life of the author plus 70 years. As an economic matter, the actual implementation of copyright law is hard to rationalize. Works with even a modicum of creativity are copyrightable. This can result in a disincentive to be creative and invites expensive legal disputes about works that are socially irrelevant. In addition, works receive levels of protection that are independent of their value to the public. In some instances Congress with the approval of the Supreme Court has extended the copyright term for works already in existence. Retroactive extension of the copyright term cannot have an impact on works in existence. Oddly, copyright law views authors as profit maximizers but also limits the value of their works by allowing heirs to terminate assignments after a set period of time. Finally, the remedy for copyright infringement is the damages suffered by the author plus all profits made by the infringer that can be traced to the infringement. It is not clear that this remedy is consistent with the goals of copyright law.

The United States has experienced an unprecedented crisis related to the misuse of and addiction to opioids. As of 2018, 128 Americans die each day of an opioid overdose, and total economic costs associated with opioid misuse are estimated to be more than $500 billion annually. The crisis evolved in three phases, starting in the 1990s and continuing through 2010 with a massive increase in use of prescribed opioids associated with lax prescribing regulations and aggressive marketing efforts by the pharmaceutical industry. A second phase included tightening restrictions on prescribed opioids, reformulation of some commonly misused prescription medications, and a shift to heroin consumption over the period 2010 to 2013. Since 2013, the third phase of the crisis has included a movement toward synthetic opioids, especially fentanyl, and a continued tightening of opioid prescribing regulations, along with the growth of both harm reduction and addiction treatment access policies, including a possible 2021 relaxation of buprenorphine prescribing regulations. Economic research, using innovative frameworks, causal methods, and rich data, has added to our understanding of the causes and consequences of the crisis. This body of research identifies intended and unintended impacts of policies designed to address the crisis. Although there is general agreement that the causes of the crisis include a combination of supply- and demand-side factors, and interactions between them, there is less consensus regarding the relative importance of each. Studies show that regulations can reduce opioid prescribing but may have less impact on root causes of the crisis and, in some cases, have spillover effects resulting in greater use of more harmful substances obtained in illicit markets, where regulation is less possible. There are effective opioid use disorder treatments available, but access, stigma, and cost hurdles have stifled utilization, resulting in a large degree of under-treatment in the United States. How challenges brought about by the COVID-19 pandemic may intersect with the opioid crisis is unclear. Emerging areas for future research include understanding how societal and health care systems disruptions affect opioid use, as well as which regulations and policies most effectively reduce potentially inappropriate prescription opioid use and illicit opioid sources without unintended negative consequences.

Criminal law consists of substantive and procedural parts. Substantive law is the set of rules defining conduct that violates the law. Procedural criminal law is the set of rules regulating the process of punishment. Substantive rules apply mostly to individual actors, and procedural rules apply to public enforcement agencies and adjudicators. Economic theory of criminal law consists of normative and positive parts. Normative economic theory, which began with writings by Beccaria and Bentham, aims to recommend an ideal criminal punishment scheme. Positive economic theory, which appeared later in writings by Holmes and Posner, aims to justify and to better understand the criminal law rules that exist. Since the purpose of criminal law is to deter socially undesirable conduct, economic theory, which emphasizes incentives, would appear to be an important perspective from which to examine criminal law. Positive economic theory, applied to substantive criminal law, seeks to explain and to justify criminal law doctrine in economic terms—that is, in terms that emphasize the incentive effects created by the law. The positive economic theory of criminal law literature can be divided into three phases: Classical deterrence theory, neoclassical deterrence, and modern synthesis. The modern synthesis provides a rationale for fundamental criminal law doctrines and also more puzzling portions of the law such as the doctrines of intent and necessity. Positive economic theory also provides a rationale for the allocation of enforcement responsibilities.

Hedge fund activism refers to the phenomenon where hedge fund investors acquire a strict minority block of shares in a target firm and then attempt to pressure management for changes in corporate policies and governance with the aim to improve firm performance. This study provides an updated empirical analysis as well as a comprehensive survey of the academic finance research on hedge fund activism. Beginning in the early 1990s, shareholder engagement by activist hedge funds has evolved to become both an investment strategy and a remedy for poor corporate governance. Hedge funds represent a group of highly incentivized, value-driven investors who are relatively free from regulatory and structural barriers that have constrained the monitoring by other external investors. While traditional institutional investors have taken actions ex-post to preserve value or contain observed damage (such as taking the “Wall Street Walk”), hedge fund activists target underperforming firms in order to unlock value and profit from the improvement. Activist hedge funds also differ from corporate raiders that operated in the 1980s, as they tend to accumulate minority equity stakes and do not seek direct control. As a result, activists must win support from fellow shareholders via persuasion and influence, representing a hybrid internal-external role in a middle-ground form of corporate governance. Research on hedge fund activism centers on how it impacts the target company, its shareholders, other stakeholders, and the capital market as a whole. Opponents of hedge fund activism argue that activists focus narrowly on short-term financial performance, and such “short-termism” may be detrimental to the long-run value of target companies. The empirical evidence, however, supports the conclusion that interventions by activist hedge funds lead to improvements in target firms, on average, in terms of both short-term metrics, such as stock value appreciation, and long-term performance, including productivity, innovation, and governance. Overall, the evidence from the full body of the literature generally supports the view that hedge fund activism constitutes an important venue of corporate governance that is both influence-based and market-driven, placing activist hedge funds in a unique position to reduce the agency costs associated with the separation of ownership and control.

Insider trading is not widely understood. Insiders of corporations can, in fact, buy and sell shares of those corporations. But, over time, Congress, the courts and the Securities and Exchange Commission (SEC) have imposed significant limits on such trading. The limits are not always clearly marked and the principles underlying them not always consistent. The core principle is that it is illegal to trade if one is in the possession of material, nonpublic information. But the rationality of this principle has been challenged by successive generations of law and economics scholars, most notably Manne, Easterbrook, Epstein, and Bainbridge. Their “economic” analysis of this contested area of the law provides, arguably, at least a more consistent basis upon which to decide when trades by insiders should, in fact, be disallowed. A return to genuine “first principles” generated by the nature of capitalism, however, allows for more powerful insights into the phenomenon and could lead to more effective regulation.

The labor market is governed by a panoply of laws, regulating virtually all aspects of the employment relation, including hiring, firing, information exchange, privacy, workplace safety, work hours, minimum wages, and access to courts for redress of violations of rights. Antidiscrimination laws, especially Title VII, notably prohibit employment discrimination on the basis of race, color, religion, sex, and national origin. Court decisions and legislation have led to the extension of protection to a far wider range of classes and types of workplace behavior than Title VII originally covered. The workplace of the early 21st century is very different from the workplace when the major employment discrimination statutes were enacted, as these laws were conceived as regulating an employer–employee relationship in a predominantly white male labor market. Prior emphasis on employment discrimination on the basis of race and sex has been superseded by enhanced attention to sexual harassment and discrimination on the basis of disability, sexual orientation, gender identity, and religion. Concerns over the equity or efficiency of the employment-at-will doctrine recede in a workforce in which workers are increasingly categorized as independent contractors who are not covered by most equal employment laws. As the workplace has changed, the scholarship on the law and economics of employment law has been slow to follow.

While economists overwhelmingly favor free trade, even unilateral free trade, because of the gains realizable from specialization and the exploitation of comparative advantage, in fact international trading relations are structured by a complex body of multilateral and preferential trade agreements. The article outlines the case for multilateral trade agreements and the non-discrimination principle that they embody, in the form of both the Most Favored Nation principle and the National Treatment principle, where non-discrimination has been widely advocated as supporting both geopolitical goals (reducing economic factionalism) and economic goals (ensuring the full play of theories of comparative advantage undistorted by discriminatory trade treatment). Despite the virtues of multilateral trade agreements, preferential trade agreements (PTAs), authorized from the outset under GATT, have proliferated in recent years, even though they are inherently discriminatory between members and non-members, provoking vigorous debates as to whether (a) PTAs are trade-creating or trade-diverting; (b) whether they increase transaction costs in international trade; and (c) whether they undermine the future course of multilateral trade liberalization. A further and similarly contentious derogation from the principle of non-discrimination under the multilateral system is Special and Differential Treatment for developing countries, where since the mid-1950s developing countries have been given much greater latitude than developed countries to engage in trade protectionism on the import side in order to promote infant industries, and since the mid-1960s on the export side have benefited from non-reciprocal trade concessions by developed countries on products of actual or potential export interest to developing countries. Beyond debates over the strengths and weaknesses of multilateral trade agreements and the two major derogations therefrom, further debates surround the appropriate scope of trade agreements, and in particular the expansion of their scope in recent decades to address divergences or incompatibilities across a wide range of domestic regulatory and related policies that arguably create frictions in cross-border trade and investment and hence constitute an impediment to it. The article goes on to consider contemporary fair trade versus free trade debates, including concerns over trade deficits, currency manipulation, export subsidies, misappropriation of intellectual property rights, and lax labor or environmental standards. The article concludes with a consideration of the case for a larger scope for plurilateral trade agreements internationally, and for a larger scope for active labor market policies domestically to mitigate transition costs from trade.

Law and economics is an important, growing field of specialization for both legal scholars and economists. It applies efficiency analysis to property, contracts, torts, procedure, and many other areas of the law. The use of economics as a methodology for understanding law is not immune to criticism. The rationality assumption and the efficiency principle have been intensively debated. Overall, the field has advanced in recent years by incorporating insights from psychology and other social sciences. In that respect, many questions concerning the efficiency of legal rules and norms are still open and respond to a multifaceted balance among diverse costs and benefits. The role of courts in explaining economic performance is a more specific area of analysis that emerged in the late 1990s. The relationship between law and economic growth is complex and debatable. An important literature has pointed to significant differences at the macro-level between the Anglo-American common law family and the civil law families. Although these initial results have been heavily scrutinized, other important subjects have surfaced such as convergence of legal systems, transplants, infrastructure of legal systems, rule of law and development, among others.

Medical malpractice is the best studied aspect of the civil justice system. But the subject is complicated, and there are heated disputes about basic facts. For example, are premium spikes driven by factors that are internal (i.e., number of claims, payout per claim, and damage costs) or external to the system? How large (or small) is the impact of a damages cap? Do caps have a bigger impact on the number of cases that are brought or the payment in the cases that remain? Do blockbuster verdicts cause defendants to settle cases for more than they are worth? Do caps attract physicians? Do caps reduce healthcare spending—and by how much? How much does it cost to resolve the high percentage of cases in which no damages are recovered? What is the comparative impact of a cap on noneconomic damages versus a cap on total damages? Other disputes involve normative questions. Is there too much med mal litigation or not enough? Are damage caps fair? Is the real problem bad doctors or predatory lawyers—or some combination of both? This article summarizes the empirical research on the performance of the med mal system, and highlights some areas for future research.

Tort law is part of the common law that originated in England after the Norman Conquest and spread throughout the world, including to the United States. It is judge-made law that allows people who have been injured by others to sue those who harmed them and collect damages in proper cases. Since its early origins, tort law has evolved considerably and has become a full-fledged “grown order,” like the economy, and can best be understood by positive theory, also like the economy. Economic theories of tort have developed since the early 1970s, and they too have evolved over time. Their objective is to generate fresh insight about the purposes and the workings of the tort system. The basic thesis of the economic theory is that tort law creates incentives for people to minimize social cost, which is comprised of the harm produced by torts and the cost of the precautions necessary to prevent torts. This thesis, intentionally simple, generates many fresh insights about the workings and effects of the tort system and even about the actual legal rules that judges have developed. In an evolved grown order, legal rules are far less concrete than most people would expect though often very clear in application. Beginning also in the 1970s, legal philosophers have objected to the economic theory of tort and have devised philosophical theories that compete. The competition, moreover, has been productive because it has spurred both sides to revise and improve their theories and to seek better to understand the law. Tort law is diverse, applicable to many different activities and situations, so developing a positive theory about it is both challenging and rewarding.