Since the attacks of 11 September 2001, international terrorism has emerged as a dominant concern in both domestic and international law and politics. The scale of the difficult questions that face democracies simultaneously trying to achieve security and maintain the principles of liberal democracy in the light of a significant terrorist attack is reflected not only in the emergence of the concept of the ‘War on Terror’ but also in the amount of law, literature and reflection that it has espoused. The attacks also ushered in an important change to the American psyche: they made Americans feel vulnerable, and they made American politicians strongly conscious of a popular demand for security to soothe that vulnerability. Americans were not alone in this: we all felt vulnerable in the wake of these attacks. Any of us observing the events of that day unfold would be hard pressed to forget the slow dawn of realisation that nothing would ever be the same again. The US had been attacked on its own soil. It had been rocked to its core and anyone who saw the towers of the World Trade Center fall must surely have been struck by the sheer audacity of the attack; of hijacking civilian aircraft and deliberately flying them into buildings in which people were beginning their working day. How could we possibly protect ourselves from such violence? What divided us from those passengers, those office workers and cleaners, those police and fire officers? Nothing did – nothing more than pure luck.