The acts of lawlessness committed on September 11, 2001 have been followed by a 'war on terror'. This book considers the law relevant to assessing how such terrorist' acts should be understood in legal terms, which responses to them are permissible and how those responses are to be pursued. It considers some of the actions that have unfolded since 9/11 (military intervention, law enforcement initiatives, human rights restrictions and abuse) prompting questions as to the 'war on terror's lawfulness. The volume clearly designates areas of international law where interest has escalated beyond traditional academic legal circles.