We are pleased to announce the International Law and Social Science Speakers Series for Fall 2025, co-sponsored by the International Law and Social Science Interest Group of the American Society of International Law (ASIL) and the Social Sciences and International Law Interest Group of the European Society of International Law (ESIL).

In recent decades, the use of traditional international treaties has declined as states increasingly rely on deformalized agreements—non-binding arrangements such as interinstitutional agreements and memoranda of understanding. These agreements allow governments to bypass the complexities of formal treaty-making while addressing shared challenges. This Article, based on four years of research and previously undisclosed agreements, examines a twenty-year database of non-binding agreements between the United States and Mexico. Through this case study, the Article demonstrates how deformalized agreements drive much of the cross-border collaboration, offering a flexible mechanism for government agencies to shape state behavior, coordinate policies, and engage in international cooperation outside the framework of formal treaties. The findings reveal that these non-binding agreements play a crucial role in shaping US-Mexico relations, influencing areas such as security, trade, and law enforcement. The study concludes that deformalized agreements are powerful instruments in modern diplomacy, raising important questions about their legal implications and future regulation by the U.S. Congress and the U.N. International Law Commission.

Author/Speaker: Guillermo Garcia Sanchez, Texas A&M School of Law

Commentator: Timothy Meyer, Duke University School of Law

Moderator: Chen Yu, City University of Hong Kong School of Law