The protection of national security has traditionally been an exception to general norms of public accountability. While prerogative powers were typically engaged, the last three decades have seen efforts to bring national security closer to the normal constitutional control mechanisms of parliament and the courts. The design of and changes to mechanisms of accountability have, however, been accepted without discussion of the often narrower purposes for which they were first established (most notably for oversight of surveillance), the extent of their departure from constitutional principles, or their impact in embedding new forms of exceptionalism in the constitutional framework. This article critically assesses these developments, prompte...