Under the Justice and Security Act 2013 and the accompanying Memorandum of Understanding, the ISC oversees the policies, expenditure, administration and operations of MI5, MI6, GCHQ, Defence Intelligence, the Joint Intelligence Organisation, the National Security Secretariat (NSS) and the Office for Security and Counter-Terrorism. The Committee sets its own agenda and work programme, taking evidence from Ministers, the Heads of the intelligence and security agencies, senior officials, experts, and academics as it considers necessary.