The international detention regime has been placed under a considerable amount of strain in the context of the war on terror. Political elites in both the USA and UK have significantly challenged accepted standards of appropriateness regarding detention, even though these states are traditionally strongly associated with the promotion of human rights internationally. Such defections and contestations present researchers with an intriguing process to understand, as these practices, by definition, challenge our settled assumptions about the post Cold-war international order. This thesis examines one element of this puzzle, assessing how the normative constraints associated with the international detention regime were negotiated by the Blair government and Bush administration so as to allow for contestation and apparent defection in 2001-2006. Generally, the IR literature on norms has focused on their constraining power, considering simple dichotomies of compliance and defection, often drawing on pre-defined interests to explain behaviour. Whilst constructivists have recognised the constitutive nature of norms, they lack a persuasive account of the micro-foundational processes of norm influence which prevents them from engaging with the contestation of seemingly embedded international normative standards. In order to address this problem I draw from the social identity approach in social psychology, where scholars focus on the multiplicity of social identities and the interactive processes of norm influence and contestation at a micro-foundational level. I demonstrate that by firmly embedding individuals in the broader social identities context and focusing on the management strategies employed by political elites we can better understand the nature of normative constraint in these cases, and whether or not an enabling framework for such counter-normative practices was established. This thesis aims to bridge some of the gap that exists between research that focuses on international norms and that which concentrates on state leaders, demonstrating the importance of the broader interactive processes of contestation, generally missing from current constructivist accounts of international norms.