In 2002, the European Parliament (EP) and the Council concluded an Interinstitutional Agreement that gave the EP privileged access to sensitive documents in the area of security and defence. It is argued that the Council let the EP become involved in this sensitive policy area because it accepted the legislature's argument for its right to access. In addition, the EP's bargaining strategy concretized the procedures and contributed to finalizing the deal after two years of negotiation. It is shown in this article that despite the EP's marginal powers in the area of security and defence and the traditional conception of this policy as an executive prerogative, it cannot be isolated from democratic principles. This article provides new evidence for previous claims that the EP's involvement in EU foreign policy is increasing due to legitimacy concerns. It also offers a theoretical account for why this is so.