Summary

Parliaments differ enormously in their foreign policy competences. This is best documented in the area of “war powers,” understood as decision-making on the use of force. In other issue areas, such as treaty-making, defense budgets, sanctions, or arms exports, differences across countries are far less researched. The available data, however, suggest that differences in those areas are no smaller than in the area of war powers. What is more, the data also show that parliamentary competences across issue areas within particular countries also differ a lot. Parliaments are not strong or weak across the full spectrum of foreign policy competences. Instead, parliamentary competences are country-specific as well as issue-specific. A general trend toward a parliamentarization or deparliamentarization of foreign affairs is not discernible.

Partly inspired by institutionalist versions of Democratic Peace Theory, numerous studies have examined whether parliamentary powers have any effect on countries’ propensity to use armed force. Case-study research tends to find that variation in parliamentary powers affects decision-making on the use of force but also emphasizes that the effects of institutional constraints need to be understood in conjunction with the preferences of the public, parliament, and government. Statistical studies have found some evidence for a “parliamentary peace,” but because of problematic indicators and a lack of controls, doubts remain about the robustness and significance of this effect. In any case, theories of legislative–executive relations in parliamentary systems suggest that open confrontations between parliament and government are exceptional. Instead of an institutional constraint in a system of checks and balances, parliamentary war powers can be understood as an additional reassurance against unpopular decisions to use force.

Most studies of parliaments in foreign affairs are characterized by “methodological nationalism”—that is, the assumption that nation-states are the natural units of analysis. However, parliaments’ activities in foreign affairs are not exhausted by their monitoring and scrutiny of national executives. In addition, there is a long tradition of “parliamentary diplomacy” and engagement in interparliamentary institutions. The most powerful parliamentary actor beyond the nation-state is the European Parliament. Although its formal competences are limited, it has been very effective in using its powers to influence European foreign policy.