How to Select and Develop International Law Case Studies: Lessons from Comparative Law and Comparative Politics

Abstract

To develop international law claims, it is often critical to study diverse states’ choices. For example, to assess whether a practice constitutes international custom, it is essential to understand whether the practice is widespread or rare. Similarly, to evaluate compliance with a treaty, it is helpful to know how different governments understand its key terms. Aware of the need for comparison, international courts, casebook and textbook authors and researchers often reference the practices of a number of different states. But these comparisons typically focus on a handful of countries that share strong linguistic, cultural, legal, socioeconomic, and political backgrounds, which is not always analytically ideal.

Where should courts, casebook authors, and researchers start their comparisons? How can they know whether they are cherry-picking examples that favor their preferred conclusions? When is it best to develop examples from countries that are very different from one’s own, and when should one focus on similar ones? And which aspects of foreign systems are most relevant for particular inquiries? The fields of comparative law and comparative politics have made tremendous progress on each of these questions. This essay synthesizes their key findings, and applies them to fundamental questions in international law.

Keywords: case selection, case analysis, methods, methodology, international, comparative