‘Regionalised collective security’ after Brexit for Europe and international law

Abstract

The United Kingdom’s decision to leave the European Union raises political and legal concerns regarding their future security and defence relationship. The UK’s current stance on establishing a security and defence relationship with the EU and Europe is that ‘NATO will remain the foundation of collective security in our home region of the Euro-Atlantic’. The ‘[c]ollective security through NATO’ policy however, is underscored by a fundamental legal question regarding the configuration and placement of regional arrangements and defensive alliances within the global security order. Regional arrangements and defensive alliances invoke the language of collective security as legal grounds for military operations home and abroad. Increasingly, such arrangements and organisations exercise their inherent right to ‘individual or collective self-defence’, in view of enacting ‘collective measures’ without explicit Security Council authorisation, out of seemingly functional necessity. And yet, the definitive character, obligations, and restrictions of these evolving security entities remains unclear. This article uses the contemporary historical event of Brexit as entry to a legal discussion concerning the distinction between defensive alliances, regional arrangements, and collective security. This article examines the gap between the loose rhetorical treatment of NATO as a collective security institution in likeness to the UN Security Council itself, and the formal legal placement of defensive alliances in the greater collective security architecture. Brexit presents a novel opportunity to assess how the contours of international security may be understood in the current and future security landscape.