Proportionality in the Use of Force

The use of force by police is regulated by both domestic law and human rights law. Under section 3 of the Criminal Law Act 1967, a person may use such force as is reasonable in the circumstances in the prevention of crime or in effecting a lawful arrest. The reasonableness of force is judged objectively, but with an important qualification: the court must consider the circumstances as the officer believed them to be, including what the officer honestly believed was necessary even if that belief turned out to be mistaken. This principle was confirmed by the Court of Appeal in R v Williams (Gladstone) [1987] and by the Court of Appeal in R v Clegg [1995].

The European Convention on Human Rights provides an additional layer of protection. Article 2 protects the right to life and provides that deprivation of life is not unlawful if it results from force that is no more than absolutely necessary. The standard under Article 2 is stricter than the domestic "reasonableness" standard: "absolutely necessary" force is a higher threshold than "reasonable" force. Where force causes death, the state must satisfy the Convention standard, not merely the domestic one. Article 3 prohibits torture and inhuman or degrading treatment, which places an absolute prohibition on certain types of force regardless of the circumstances.

In practice, proportionality requires officers to consider: what is the threat or risk that force is intended to address; is there a less forceful option that could achieve the same objective; is the degree of force contemplated proportionate to that threat; and what is the likely impact on the subject. The National Decision Model provides a framework for working through these questions in real time. An officer who uses force must be able to justify each element of that force in terms of what they knew or reasonably believed at the time.

Restraint techniques used by police are subject to particular scrutiny following a number of deaths in custody and in the community. The positional asphyxia risk associated with certain prone restraint positions has led to guidance from the College of Policing advising officers to move restrained persons to a recovery position as quickly as possible. Training in authorised restraint techniques is mandatory, and officers who use techniques outside their training may face criminal prosecution or misconduct proceedings.