Whistleblowers promote the values of responsible government and the rule of law by drawing attention to criminal or other forms of wrongdoing in publicly accountable organisations. This article explores the relationship between whistleblowing, national security and the implied freedom of political communication under the Australian Constitution. Legislation such as the Crimes Act 1914 (Cth) (‘Crimes Act’), the Australian Security Intelligence Organisation Act 1979 (Cth) (‘ASIO Act’) and the Australian Border Force Act 2015 (Cth) (‘Border Force Act’) makes it an offence to reveal certain types of information obtained as a Commonwealth officer. The Public Interest Disclosure Act 2013 (Cth) (‘PIDA’) offers limited protection to whistleblowers in the Commonwealth public sector, but this protection does not extend to information relating to intelligence operations. We argue that blanket criminalisation of unauthorised disclosure by Commonwealth officers or contractors under s 70 of the Crimes Act, along with s...