Parliamentary oversight requires accessibility of information. In foreign and security policy however, executive institutions have possession and discretion over (sensitive) information. Practice shows that oversight at times is not activated at all due to ‘deep secrets’, i.e. parliaments are unaware of certain executive action or its scope (the case with the PRISM programme and U.S. Congress), or information is limited to such extent that it impacts the capacity of parliaments to exercise control (the European Parliament regarding the SWIFT Agreement). This paper shows the dynamic and continuous process of adjustment of powers between parliaments and executive institutions in access to information. The paper argues that often accessibility to information becomes the main point of contention, curtailing institutional resources and detracting from debates on policy issues.