The Police and Criminal Evidence Act 1984 (PACE) sets out a number of rules regarding the procedure the police must follow before and during arresting someone. Under section 24 PACE, a lawful arrest has two key elements:

• A person’s suspected, attempted or actual involvement in the commission of a criminal offence

and

• Reasonable grounds for believing that the person’s arrest is necessary.

Both of these conditions must be satisfied, and the police officer must make the person being arrested aware that they are being arrested, both conditions are satisfied and why.

An arrest can only be necessary to:

• Enable the name of the person in question to be ascertained;
• Enable the address of the person in question to be ascertained;
• Prevent the person being injured, causing damage to property, committing an offence against public decency or causing unlawful obstruction of a highway;
• Protect a child or vulnerable person;
• Allow prompt and effective investigation of the offence or the conduct of the person; or
• Prevent the person disappearing.

Upon arrest, unless exceptional circumstances exist, a person must be given a caution and a record of arrest must be made.