Security Service Act 1989

The British Act that sets out the role of MI5, namely the protection of national security.

According to MI5, its role is defined in this Act.¹

Section 1(1) as originally enacted: “There shall continue to be a Security Service (in this Act referred to as ‘the Service’) under the authority of the Secretary of State.” The word “continue” means that the Act did not create MI5; it gave a statutory basis to a service that had existed since 1909.^2,3

Section 1(2): “The function of the Service shall be the protection of national security and, in particular, its protection against threats from espionage, terrorism and sabotage, from the activities of agents of foreign powers and from actions intended to overthrow or undermine parliamentary democracy by political, industrial or violent means.” Subsection (3) adds the task of safeguarding the “economic well-being of the United Kingdom” against threats posed by persons outside the British Islands. The foreign intelligence service (SIS) and GCHQ were given a statutory basis only in the Intelligence Services Act 1994.^2,4

More in the service card: MI5 (Security Service).