The legal response to transnational terrorism is constantly evolving. For example, after the unprecedented destruction caused by the 9/11 attacks, there was a shift towards the use of military force as the primary tool in transnational counter-terrorism (CT), rather than an approach based on a law enforcement paradigm. However, CT is not simply a choice between either military or law enforcement options. Both approaches remain vital and have become more refined over time, facilitated by an increased level of international cooperation guided by the rule of law. However, much work remains to be done.
This chapter begins with a brief discussion of strategic considerations of military versus law enforcement approaches to CT, with particular focus on the issues of legitimacy, liberty and security. The military legal regime is then explored in greater depth, with a focus on key challenges currently faced by CT professionals in this area. This is followed by a discussion of the law enforcement regime with an emphasis on international cooperation and the continued development of law enforcement tools needed to investigate and bring terrorists to justice.