The rule of law is one of the oldest principles of democratic governance. It is a fundamental principle of the European Union (EU), found in Article 6(1) of the Treaty on European Union. In this jurisdiction, it can be said to entail a community of law and principles of protection for individuals and of rational procedures. In other jurisdictions, most notably the United States, the rule of law has been significantly eroded in the context of the 'war on terrorism'. One cause of this erosion is the adoption of pre-emptive measures which are rooted in late twentieth century risk society thinking. As risk society thinking is also prevalent in EU policy-making, the thesis considers whether fundamental rule of law principles have also been eroded in this legal order. The study critically examines key EU counter-terrorism measures, adopted since September 11 2001, to ascertain how rule of law principles have been affected in the 'war on terrorism'. The thesis draws on the work of Michel Foucault to characterise EU counter-terrorism as a 'pre-emptive dispositif. Five key facets of EU counter-terrorism efforts are analysed. First, the common European definition of terrorism is examined, along with related offences contained in the Framework Decision on Combating Terrorism (as amended). Second, the EU's numerous anti-money laundering and counter-terrorist finance laws are investigated. Third, UN and EU targeted asset-freezing sanctions are critiqued. Fourth, certain elements of the EU's data retention policies and relevant legal measures are considered. Fifth, the European Arrest Warrant and European Evidence Warrant are examined. The thesis concludes that while the EU does not possess the strong coercive powers of its Member States and it has generally avoided the use of the 'war' strategy in its counter-terrorism efforts, the effect of its counterterrorism action on the rule of law has been profound.