The citizen’s arrest is an important tool in preventing crime and catching criminals but performing one can be illegal – even if a crime is taking place.

If you see a crime taking place or see a suspect fleeing you can use ‘reasonable force’ to stop them until the police have time to arrive.

Citizens are encouraged to help in the prevention and investigation of crime where it is responsibly done and in the public spirit.

But if you get it wrong you can find yourself charged with assault, false imprisonment and other offences.

And if you injure the suspect, even accidentally, you can be sued.

So when can you intervene and what constitutes ‘reasonable force’?

Solicitor DAS Law have produced a guide to keeping on the right side of the law should you need to play the hero.

What can I do to stop and detain a suspect?

Anyone can make a citizen’s arrest if they believe an indictable offence is or has been committed.

An indictable offence is one that would be dealt with in a crown court. It covers the most serious offences but also includes robbery, substantial criminal damage and assault causing ‘actual bodily harm’.

They must be reasonable grounds for suspecting a crime is being – or has been – committed.

Also there must be no reasonable possibility that a police officer doing this instead. For example, this cause arise if the police are yet to arrive and the suspect is likely to escape.

What can I NOT do?

The purpose is to uphold the law rather than taking the law into their own hands for the purposes of revenge, retribution or vigilantism.

If you use excessive force you could be prosecuted for assault – or worse.

You could find yourself on the wrong side of civil claim if the suspect is injured.

Charges of wrongful arrest, unlawful restraint and false imprisonment may also apply if the person was innocent and had been falsely suspected of a crime.

How do I make a citizen’s arrest?

There is no specific wording to use when making a citizen’s arrest.

However you must inform the person you are arresting of what you are doing, why you are doing it and what offence you believe they have committed as soon as possible.

You can only use reasonable force throughout this process.

You should call and deliver the person to the police immediately.

What is ‘reasonable force’?

There is no definitive definition of reasonable force but the amount of force you use should be proportionate to the threat posed by the suspect. For example, if suspect is running away from you with no intention of causing you harm you would be more limited in the force you could use than in a situation where the suspect was brandishing a knife at you.