The post -Cold War period has seen substantial evolution in the relationship between law and war. l It has seen considerable development in the field of the Laws of Armed Conflict as well as considerable change in the character, if not the nature, of contemporary warfare and marked developments in the international political arena, most notably regarding action in response to threats to international peace and security.2 Although the full impact of these changes has yet to be realised, the relationship between war, crime and legitimacy has been brought sharply into focus with regard to a number of recent events that have given rise to heated debate. 3 From decisions about whether and when to use force, to dilemmas over how force should be deployed, issues of legality and legitimacy have featured prominently. The changing character of warfare, leaving behind more conventional forms, has stretched and tested a body of law designed, in the main, for conventional armed conflicts, requiring reflection, adaptation, interpretation and, in some cases, possibly requiring new legal instruments. This chapter considers four areas, in this context, that have given rise to heated debate in the context of the 'war on terror': extended discussion of self-defence to the notion of 'targeted killings'; the issue of detaining quasi-Prisoners of War in the context of a form of transnational conflict that, as a non-international, is not covered by the Geneva Convention on Prisoners of War; irrespective of their formal status, the abusive treatment of individuals detained by US and coalition forces in camps based at Guantanamo Bay and elsewhere, including the difficult topics of rendition, torture and abuse that came to mark the US mission; extension of the latter, the juridification of armed conflict - with the UK example to the fore.