This paper investigates Australia’s National Security Information (Criminal and Civil Proceedings) Act 2004 (Cth) (hereafter, the NSI Act) focusing on its provisions for protecting national security information. The investigation highlights the broad and encompassing definitions of ‘national security’ and ‘information’ used in the Act and considers the measures it prescribes for the protection of so-called ‘security sensitive’ information in Federal civil and criminal proceedings. The paper then examines the implications of the definitions and measures for a suspect’s prospects of receiving a fair trial in terrorism cases. Here, the paper highlights the serious restrictions the Act places on a legally-aided person’s right to engage a legal representative of their own choosing. These restrictions are then compared with those obtaining in some comparable jurisdictions. As important as the NSI Act’s definitions and measures are for the way in which they limit a terrorism suspect’s chances of a fair trial, their significance extends well beyond this very serious issue to even deeper concerns. These relate to the secrecy and lack of transparency surrounding the conduct of terrorism cases, the opaqueness of the processes for classifying and protecting information, and the potential for tendentious or improper use of information by the political executive and national security agencies enabled by the dearth of avenues for external, independent scrutiny. At the core of these concerns, then, are issues of the accountability and integrity of the government and of the agencies under its direction. Using the experience of Mohamed Haneef as a case study, the final section of the paper investigates the important role that defence counsel, the media and other independent parties can play to facilitate public scrutiny of the conduct of terrorism investigations and trials and in exposing the improper use sometimes made of protected information by the political executive in attempting to influence the conduct of these cases.