The New Transatlantic Trigonometry: “Brexit” and Europe’s Treaty Relations with the United States

The withdrawal of the United Kingdom from the European Union is not only a source of political and legal upheaval in Europe but will prompt a recalibration of transatlantic treaty relations. The paper argues that it is a gross oversimplification to conceive of the latter as sets of old and new bilateral relationships. Instead, “Brexit” affects many existing and interdependent triangular relationships that the U.S. maintains with the EU and its Member States, which are conditioned also by the foreign relations laws of these polities. Perhaps counterintuitively, recalibration in the “high politics” area of security and defense will be easier than in the “low politics” of trade and regulation. In elaborating on these arguments, the paper delves into three levels of difficulty: First, the empirical challenge of determining the treaties in force between the EU and U.S. and by which the UK will cease to be covered; second, the transatlantic implications of available alternative models to EU membership for the UK; and third, the way forward in ensuring continuity and bringing about future agreements and cooperation in the EU-UK-U.S. triangle, seeing that the EU itself is a moving target due to ongoing reform efforts.