The terrorist attacks of 9/11 triggered a security crisis in the EU, which led to the realisation that international terrorism requires a common European strategy to combat it. Consequently, the European Council adopted various action plans and strategy papers defining measures in the fight against terrorism, which are to be assigned to policy areas that were previously under the sovereignty of the nation states: Justice and Home Affairs (JHA) and Foreign and Security Policy. Based on the three leading integration theories (Liberal Intergovernmentalism, Post-Functionalism, Neo-Functionalism), a qualitative content analysis has been carried out to explore the extent to which 9/11 has influenced the EU integration process. Despite considerable initial difficulties in the post-9/11 period, the terror attacks in Madrid and London in 2004/2005 led to considerable developments with a supranational approach in the JHA and common foreign and security policy (CFSP). However, in the fight against terrorism, the EU seems to be facing a conflict of goals with its integration objective of the establishment of an Area of Freedom, Security and Justice (AFSJ). A second content analysis of two anti-terrorism measures - the European Arrest Warrant and data retention - has shown considerable deficits in democratic, legal and social legitimacy. The partial lack of parliamentary and judicial control, limited transparency and weak protection of human rights make it clear that the aspect of security is at the forefront in the common anti-terrorism policy. The EU appears to accept significant restrictions on freedom, the rule of law and the protection of human rights when it comes to defending Europe against terrorism. Given the EU's inability to fulfil its self-imposed obligations concerning an AFSJ, the argument is made that the EU must shift its focus towards a balance between freedom, security and justice if it does not want to undermine its own legitimacy.The terrorist attacks of 9/11 triggered a security crisis in the EU, which led to the realisation that international terrorism requires a common European strategy to combat it. Consequently, the European Council adopted various action plans and strategy papers defining measures in the fight against terrorism, which are to be assigned to policy areas that were previously under the sovereignty of the nation states: Justice and Home Affairs (JHA) and Foreign and Security Policy. Based on the three leading integration theories (Liberal Intergovernmentalism, Post-Functionalism, Neo-Functionalism), a qualitative content analysis has been carried out to explore the extent to which 9/11 has influenced the EU integration process. Despite considerable initial difficulties in the post-9/11 period, the terror attacks in Madrid and London in 2004/2005 led to considerable developments with a supranational approach in the JHA and common foreign and security policy (CFSP). However, in the fight against terrorism, the EU seems to be facing a conflict of goals with its integration objective of the establishment of an Area of Freedom, Security and Justice (AFSJ). A second content analysis of two anti-terrorism measures - the European Arrest Warrant and data retention - has shown considerable deficits in democratic, legal and social legitimacy. The partial lack of parliamentary and judicial control, limited transparency and weak protection of human rights make it clear that the aspect of security is at the forefront in the common anti-terrorism policy. The EU appears to accept significant restrictions on freedom, the rule of law and the protection of human rights when it comes to defending Europe against terrorism. Given the EU's inability to fulfil its self-imposed obligations concerning an AFSJ, the argument is made that the EU must shift its focus towards a balance between freedom, security and justice if it does not want to undermine its own legitimacy.