Law and Governance

MI5 works within a strict framework of legislation and oversight to ensure our investigative powers are only used where it is necessary and proportionate to do so. Our work is subject to rigorous scrutiny: by the Home Secretary, who personally signs warrants for our most intrusive activity; by Parliament, in the Intelligence and Security Committee; and by the Investigatory Powers Commissioner’s Office and Judicial Commissioners who are involved in the authorisations of our warrants and the overseeing of our use of such authorisations.

Role and responsibilities

The statutory basis under which MI5 operates is set out in the Security Service Act 1989 (SSA). The Act sets out our functions and gives some examples of the nature and range of threats that we are responsible for countering.

In summary our functions are:

• to protect national security 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;
• to safeguard the economic well-being of the UK against threats posed by the actions or intentions of persons outside the British Isles; and
• to act in support of the activities of the police forces and other law enforcement agencies in the prevention and detection of serious crime. 

In a democracy, a domestic security service must be apolitical and accountable. The Act places us under the authority of a Secretary of State, in practice the Home Secretary, who is accountable to Parliament for the work of MI5.

The Act also sets out the Director General's responsibilities in law for ensuring that we do not act to further the interests of any political party. Our role is to protect democracy, not to influence its course. The government of the day cannot instruct MI5 to perform any action for party political reasons.

The right to respect for private and family life

Article 8 of the European Convention on Human Rights (ECHR) asserts the right to respect for private and family life, home and correspondence. It states that public authorities should not interfere with this right, except in specific circumstances, and this obligation is embodied in the UK through the Human Rights Act 1998.

MI5’s functions are recognised in Article 8 as providing a legitimate basis, in appropriate cases, for interference with an individual’s right to respect for their privacy. Leander v Sweden (1987) established that a state can pursue these functions through a security service that has a clear legal basis.

The state should also ensure that there are adequate and effective guarantees against abuse. The Investigatory Powers Act 2016 establishes mechanisms for the oversight and control of MI5’s activities.

Intelligence gathering

The Security Service Act 1989, the Investigatory Powers Act 2016, the Regulation of Investigatory Powers Act 2000 and the Intelligence Services Act 1994 provide a legal framework for our intelligence gathering activities.  These activities include the use of covert surveillance and covert human intelligence sources, interception of communications, acquisition of communications data, equipment interference, and entry on or interference with property or wireless telegraphy.  The Investigatory Powers Act also provides for the bulk interception of overseas-related communications, the bulk acquisition of communications data, and the retention and examination of bulk personal datasets.

Covert surveillance which is not intrusive, the use of covert human intelligence sources and the acquisition of communications data must be authorised by designated persons within MI5.  All other intelligence gathering activity must be authorised by a warrant signed by a Secretary of State, usually the Home Secretary.  A warrant or authorisation may only be issued where the action is necessary and proportionate in the interests of national security, or for one of our other statutory functions.  
 

Oversight of Investigatory Powers

The Investigatory Powers Commissioner’s Office  (IPCO) is the independent oversight body for MI5’s investigatory powers.  It is made up of the Investigatory Powers Commissioner and a number of other Judicial Commissioners who are responsible for ensuring that MI5’s use of their investigatory powers is lawful, necessary and proportionate.  This oversight responsibility is met through a comprehensive ongoing review process, which includes audit, inspection and investigation.  In particular, the Judicial Commissioners must keep under review the operation of safeguards to protect privacy.

All MI5 warrants, in addition to being authorised by a Secretary of State, must also be reviewed and approved by a Judicial Commissioner who will apply the same principles as would be applied by a court on an application for judicial review.

IPCO oversight functions extend to also having sight of MI5 warrants throughout the 'double lock' process. This consists of a Judicial Commissioner reviewing MI5 warrants once they have been approved by the Home Secretary, and only authorising the warrant if they feel that the warrant is necessary and proportionate in the interest of MI5's statutory functions.

Access to information

An individual has the right to access information about them which is being processed by MI5.  This right is contained in section 94 of the Data Protection Act 2018.  Members of the public can also request information from MI5 under the Environmental Information Regulations.

For more information about this, see Access to information.

Police powers and restrictive measures

The Terrorism Act 2000, Anti-Terrorism, Crime and Security Act 2001, Terrorism Act 2006 and Counter-Terrorism Act 2008 have defined and expanded the range of criminal activities related to terrorism, and police powers to deal with them.

The Terrorism Prevention and Investigation Measures (TPIMs) Act 2011 introduced TPIMs to reduce the risk from people believed to be engaged in terrorism-related activity who cannot be prosecuted or deported. The restrictive measures are more tightly proscribed than those previously available under control orders, which TPIMs replace.