The beginning of President Donald J. Trump’s second term in office has been marked by dramatic changes in the U.S. government’s approach to foreign policy, international law, and international organizations. That, at least, is the predominant view both in the United States and abroad. At the same time, President Trump’s executive orders and other policy directives have come so quickly, addressed so many issue areas, taken so many forms, and been so disruptive that they are nearly impossible for any single person to document, let alone to evaluate comprehensively and carefully. Much coverage of them to date has been piecemeal, superficial, or politically charged.

In response, we invited our Board of Editors to analyze the events that have unfolded in their areas of expertise. Our goal is to provide an introduction and overview of the U.S. government’s actions across a wide range of international legal issues since the beginning of President Trump’s second term. The result is this special issue of the American Journal of International Law dedicated to the Contemporary Practice of the United States. It documents and analyzes U.S. practice across a broad range of issue areas, from immigration to international organizations to climate and the environment, tariffs, immunities, war powers, and outer space, with perspectives from Africa, Asia, Europe, and Latin America. Each essay analyzes the core legal issues involved, including by discussing whether or how the U.S. practice at issue is unprecedented.

We believe that the U.S. practice during this period is contributing to broader trends that together will alter the trajectory of international law. We hope that the clear and sharp analysis in these essays provides the foundation for efforts to understand and shape what comes next.