Since 9/11, the agenda of the international community has been shaped, and perhaps dominated, by the fight against terrorism. Preceding chapters have explored in detail particular areas of the relevant international legal framework, alongside particular responses to international terrorism post-9/11. This concluding chapter considers this practice as a whole, reflecting on certain overarching characteristics of the ‘war on terror’ and its approach to international legality. It then considers the legal framework itself, and the extent to which the experience of terrorism and counter-terrorism have indicated – as some have asserted – gaps and inadequacies in the law, or led to a transformative shift in the international legal order. It suggests that there are no gaping holes in that framework, while highlighting pockets of legal development, tensions and areas where the law may yet be subject to development. The chapter ends by questioning the longer-term implications of the ‘war on terror’ for the rule of law.

9/11: tragedy, opportunity and the ‘war on terror’ response

9/11 was an international tragedy. It was a crime under international law and, as the Security Council promptly determined, a threat to international peace and security. It was followed by widespread, perhaps unprecedented, expressions of international solidarity with the US. The Security Council expressed its willingness to act, and for the first time in history, NATO asserted the right of collective self-defence. States and institutions committed their shared determination to cooperating more effectively to combat terrorism and to hold to account those responsible.