Foreign relations law focuses on the domestic institutions that conduct a state’s relations with foreign actors, whether states, international organizations, or foreign persons. One of its tasks is to intervene between international and domestic law. This function makes us think about international law as embraced and implemented by states (or not), rather than the workings of the international community (whatever that may be). Foreign relations law takes us at least one step away from the conventional conception of international law as a uniform and universal body of rules and standards. At the most general level, foreign relations law provides part of an explanation for the similarities and differences in the practice, methodology, and ideology of international law among states that comparative international law studies.

Some see the contemporary version of foreign relations law as an attempt to undermine the significance and power of international law. Perhaps the same critique could be directed at comparative international law as well as at the fragmentation literature. This chapter takes up the normative challenge. It defends both foreign relations law and comparative international law as ways of ensuring that international law remains relevant to problems of international cooperation and the advancement of human flourishing in an increasingly challenging world.

The discussion proceeds in three sections. The first describes contemporary foreign relations law as a distinct field that emerged in the United States in the late 1990s and developed independently in parts of the British Commonwealth and Europe. It traces the parallels with and differences between foreign relations law and comparative international law. The second section considers the possibility that these complementary trends, as well as new concerns about fragmentation in international law, pose a threat to international law as conventionally conceived. Are all three of these developments different aspects of a general turn away from international law? The third section responds to these concerns. It argues that all these challenges may strengthen international law as a resilient and helpful means for meeting the growing and greater demands that the contemporary world places on it.

The above is an excerpt of Chapter 3 from the book Comparative International Law. Click here for the full Chapter, written by Paul D. Stephan. The complete book is available at SSRN: https://ssrn.com/abstract=3139978.