When may police use force, and what limits apply?

The reason force is regulated so tightly is that it is the point at which the state acts on a person directly and irreversibly. A wrongful arrest can be undone by a court. A wrongful use of force frequently cannot be undone at all.

AnalysisThe framework therefore does not treat force as a tool to be used efficiently. It treats it as a last resort whose use has to be justified afterwards, which is why the rules are written as duties on the official rather than as entitlements.

The 1979 United Nations Code of Conduct for Law Enforcement Officials, a General Assembly resolution of 17 December 1979, is the earliest of the two central instruments in this area. It is a resolution rather than a treaty, so it binds no state by itself.

The duty to try something else first is stated in the plainest terms the instruments contain.

Principle 4 of the 1990 Basic Principles provides that officials "shall, as far as possible, apply non-violent means before resorting to the use of force and firearms", and "may use force and firearms only if other means remain ineffective or without any promise of achieving the intended result". The non-violent means contemplated are ordinary ones: the visible symbols of police authority, body language, and verbal persuasion.

Legitimate purpose

Article 3 of the 1979 Code of Conduct permits force only "to the extent required for the performance of their duty". Its official commentary reads that as no more force than "is reasonably necessary under the circumstances" — for example to prevent crime or to effect a lawful arrest.

Minimum reasonable force

When force is necessary at all, it must be the least that will do. The requirement is not that some force was justified, but that this much force was.

The need can expire

No additional force is lawful once the need has passed — for instance once a person is safely and lawfully detained. Force is licensed by a continuing purpose, not by the earlier existence of one.

Precaution

Planning and equipment are part of the assessment, not preliminaries to it. Principle 3 addresses self-defensive equipment such as shields, helmets and bulletproof vests, on the reasoning that better-protected officials need to resort to force less often.

The same framework states four things force may never be: used vindictively, used as a form of extrajudicial punishment, applied in a discriminatory manner, or applied to a person offering no resistance.

The obligation runs in both directions. Officials are themselves entitled to the protection of their rights to life and to bodily integrity, which is part of why equipment and planning are treated as duties of the institution rather than choices of the individual.

• Common belief: If an officer was legally entitled to use force, the amount used does not matter.

  In practice: Entitlement and extent are separate questions, and the second is where most assessments actually turn. A use of force can begin lawfully and become unlawful — most obviously once the need that justified it has passed.

• Common belief: The rules are the same everywhere because the international standards are the same.

  In practice: The international principles are widely shared; the domestic tests that apply to a specific incident are not. Countries that all accept necessity and proportionality still differ on thresholds, on when firearms may be drawn, on reporting duties, and on who reviews the decision afterwards.

• Common belief: Use-of-force rules exist to protect the public from the police.

  In practice: They do that, and they also define the officer’s protection. A use of force that meets the standard is defensible precisely because a standard exists; without one, every incident would be judged by hindsight and public reaction.

• Common belief: Compliance with the standard is a matter of the officer’s judgement alone.

  In practice: The framework places duties on the institution as well: equipment, training, planning, and the reporting that allows a decision to be reviewed. Treating force as purely an individual decision is one of the commonest ways an institutional failure is recorded as a personal one.

Almost everything below the level of the principles varies, and the variation is not cosmetic.

• Whether officers routinely carry firearms at all is a national policy question answered differently by neighbouring countries with similar legal traditions.
• The domestic legal test — how "necessary" and "proportionate" are defined, and against whose perspective they are measured — is set by national law and case law.
• What must be reported after force is used, to whom, and within what period, differs widely; so does whether an external body is notified automatically.
• Which body reviews a serious incident ranges from the officer’s own service, to a separate national investigative body, to a prosecutor or investigating judge.
• Regional instruments add their own standards. The 2001 European Code of Police Ethics, for example, provides that police may use force "only when strictly necessary and only to the extent required to obtain a legitimate objective".

Because the domestic test is what governs any actual incident, the country pages are the right place to look for a specific system — for example law enforcement in France, in Japan, or in the United States.

A standard that is never checked is a statement of intent. What converts the use-of-force framework into an accountability mechanism is the record: what happened, what was tried first, what was decided, and by whom.

• Reporting requirements are what make review possible at all; an unreported use of force is not reviewable regardless of whether it was justified.
• The Universal Declaration of Human Rights states the declared principles most directly engaged, including the right to an effective remedy.
• Serious incidents are, in many systems, removed from the employing service and given to an external investigator — a design choice examined in how police are held to account.

The right to an effective remedy for acts violating fundamental rights is stated in the Universal Declaration of Human Rights.

• This guide states the international framework. It does not state the legal test that applies in any particular country, because that test is set by domestic law and differs — sometimes substantially — between jurisdictions that have all accepted the same international principles.
• The primary instruments quoted here are published by OHCHR, whose site refuses automated access. The wording below is quoted as it appears in a United Nations Office on Drugs and Crime teaching module that reproduces it, and is attributed that way rather than to a copy we could not open.

Related: why police accountability matters, arrest and detention, and why societies need law enforcement. The necessity and proportionality on this page measure an action against its objective; the constitutional doctrine that measures a rule against a right is what proportionality requires. How much training time is measurably spent on this, and on the law that limits it, is what police recruits are taught.