Legislatures are critical to international law governance for two related reasons. First, most are involved in several stages of treaty creation and operation, including their formation, interpretation, implementation, and application. Second, this impact is compounded by legislators’ different preferences concerning international governance issues and state behavior. Despite these things, the international law (IL) and international relations (IR) literatures have given legislatures’ fairly little attention. For its part, IL scholarship has focused its domestic attention almost entirely on courts and executives in foreign relations. Yet how IL operates in national governments is commonly a result of non-legal, political processes. Studies that purport to gauge how IL affects a domestic legal system should therefore consider how statutory interpretations are often the foundation for later judicial and executive interpretations. IL research should more closely consider the determinants of legislative domestic interpretation. In contrast, IR scholarship has traditionally (though less so recently) explained international behavior by assuming a unitary state interest, thereby overlooking the substantial variety of legislative influences on state behavior. More of this research should take seriously the lessons of the liberal IR school: for instance, that a state’s externally expressed preference often depends on how that preference is aggregated domestically through lawmaking processes. Importantly, that preference aggregation can change based on subject matter (executive agreement, military action, treaty, customary law formation) and on domestic political winds.
Citation
Kevin Cope, Treaty Law and National Legislative Politics, in Research Handbook on the Politics of International Law, Edward Elgar, 116–148 (2017).