The Intelligence and Security Committee of Parliament (ISC) was first established by the Intelligence Services Act 1994 to examine the policy, administration and expenditure of the Security Service, Secret Intelligence Service (SIS), and the Government Communications Headquarters (GCHQ). The Justice and Security Act 2013 reformed the ISC: making it a Committee of Parliament; providing greater powers; and increasing its remit (including oversight of operational activity and the wider intelligence and security activities of Government). Other than the three intelligence and security Agencies, the ISC examines the intelligence-related work of the Cabinet Office including: the Joint Intelligence Committee (JIC); the Assessments Staff; and the National Security Secretariat. The Committee also provides oversight of Defence Intelligence in the Ministry of Defence and the Office for Security and Counter-Terrorism in the Home Office.

Members of the ISC are appointed by Parliament and the Committee reports directly to Parliament. The Committee may also make reports to the Prime Minister on matters which are national security sensitive.

The Members are subject to Section 1(1)(b) of the Official Secrets Act 1989 and have access to highly classified material in carrying out their duties. The Committee takes evidence from Cabinet Ministers and senior officials – all of which is used to formulate its reports.