What does "reasonable force" mean and when can police use it?

The concept of reasonable force runs through the law of policing and self-defence. For police officers, the primary source is section 117 of PACE 1984, which permits the use of reasonable force whenever a power under PACE is exercised. The Criminal Law Act 1967 section 3 provides a broader authority: any person, including a police officer, may use such force as is reasonable in the circumstances for the purpose of preventing crime or assisting in the lawful arrest of offenders or suspected offenders.

Whether force is reasonable depends on the circumstances at the time it was used, not in hindsight. Courts apply the following principles: Was force necessary at all? Was the degree of force used proportionate to the threat? Did the officer honestly believe (even if mistakenly) that force was necessary? An officer acting on a genuine but mistaken belief about the need for force may still be acting lawfully if the mistake was reasonable.

The National Decision Model (NDM) is the framework used by police in England and Wales to make decisions in dynamic situations, including decisions to use force. It requires officers to consider the threat or risk, the powers and options available, and the proportionality of those options.

Excessive force is unlawful. Where an officer uses force that is disproportionate or unnecessary, this can amount to a criminal offence (assault or, in extreme cases, manslaughter or murder), a civil wrong giving rise to a claim in tort, and a misconduct matter under the Police (Conduct) Regulations 2020.

Members of the public also have the right to use reasonable force in self-defence or in defence of others, governed by section 76 of the Criminal Justice and Immigration Act 2008.

Key Points

• Reasonable force must be necessary and proportionate to the threat in the circumstances
• Officers have statutory authority to use reasonable force under section 117 of PACE and section 3 of the Criminal Law Act 1967
• The National Decision Model guides police decisions about the use of force
• Force is judged from the perspective of the officer at the time, not with hindsight
• An honest but mistaken belief about the need for force may still be lawful if the belief was reasonable
• Excessive force is unlawful and can lead to criminal charges, civil liability, and misconduct proceedings
• Members of the public can also use reasonable force in self-defence under section 76 of the Criminal Justice and Immigration Act 2008