Cass Sunstein, a noted American constitutional scholar, once lamented: ‘The notion that the government may control information at its source is at odds with the idea that the purpose of a system of free expression is to control the conduct of representatives.’ In a liberal democracy – supposedly of the people, by the people, for the people – political opacity is inconsistent with the central premise of government.

Yet in Australia, and elsewhere, this overriding presumption of governmental transparency has been steadily eroded. As veteran journalist Brian Toohey reveals in his sweeping new book, Secret: The making of Australia’s security state, which begins with words from Australia’s defence minister of 1938 and concludes in the Scott Morrison era, the catchcry of national security has time and again distorted our political system. From a default position of openness, with limited exceptions only where justified by compelling interests, secrecy has become the norm.