A legal guide to citizen's arrest

Although better left to the police, Rupert Myers explains the law when performing a citizen's arrest

Following the revelation that the TV historian Dan Snow rugby-tackled a rioter in London it seems timely to produce a basic guide to the citizen's arrest. I've seen a few incidents of people intervening to try and prevent crime. Some of them have been successful, and others have resulted in those people becoming the victim of violent crime themselves. It's always better to leave it to the professionals if you can, but the criminal justice system accepts that isn't always possible. Hence the existence of law which amounts to what is commonly known as the citizen's arrest.

The law is certainly not a vigilante's charter: the starting point is that detention of another person is, on its own, unlawful. The statutory power of any member of the public in England and Wales to detain someone they consider to be involved in criminal activity is to be found in section 24A of the Police and Criminal Evidence Act 1974. A person "other than a constable" may arrest without a warrant anyone:

Who is in the act of committing an indictable offence; or whom the person has reasonable grounds to suspect is committing an indictable offence.

An indictable offence is one that can be tried in a crown court, in front of a jury. This alone isn't much use to the average civilian, and astonishingly the government doesn't seem to publish a complete list of offences which qualify, but examples include theft, criminal damage and assault occasioning actual bodily harm.

Such an arrest can only be made if it does not appear reasonably practicable for a police constable to make the arrest instead, and if the person making the arrest has reasonable grounds to believe that such an arrest is necessary to prevent the person being arrested from: (a) causing physical injury to himself or any other person; (b) suffering physical injury; (c) causing loss of or damage to property; or (d) making off before a constable can assume responsibility for him.

Anyone attempting such an arrest should also inform the subject of what is being done doing as soon as is reasonably possible, explaining the reason for arresting them, and what offence it is believed that they have committed. Anyone carrying out an arrest can only use reasonable force when arresting the person in question. This is a matter of degree, obviously.

A civilian also has a broader (if somewhat vaguer) common law (i.e. judge-made) power of arrest where there is a "breach of the peace", which itself is not really a crime, but can be said to occur whenever harm is actually done or is likely to be done to a person or, in his presence, to his property, or where a person is in fear of being harmed through an assault, affray, riot, unlawful assembly or other disturbance.

A civilian may conduct an arrest in these circumstances if: (a) a breach of the peace is committed in his presence, (b) the person effecting the arrest reasonably believes that such a breach will be committed in the immediate future by the person arrested, or (c) a breach of the peace has been committed or the person effecting the arrest reasonably believes that a breach of the peace has occurred and that a further breach is threatened.

If it goes to court for some reason, the court will determine whether the belief was reasonable having regard to the circumstances as perceived by the person carrying out the arrest at the time. Where a reasonable apprehension of an imminent breach of the peace exists, the preventive action taken must be reasonable and proportionate.

On a practical level, it is usually best to avoid getting involved as this story and this story show.

If you do intervene, do so carefully, respectfully, and with, at most, a reasonable and proportionate use of force — only having first checked that there is no possibility of a police officer doing the job for you. Always call the police, and make sure that anyone you have arrested is transferred to the police as soon as possible.

Avoid acting alone, since if the person you have arrested later tries to suggest that you have assaulted them, or caused them some other wrong, you don't want to find that it is just your word against theirs. Any video or sound recording of what led you to act, or the testimony of any friend or relative who watched the whole incident may be helpful when it comes to explaining to the police and to the Crown Prosecution Service why you have stepped in to the breach.

Rupert Myers is a barrister specialising in criminal law