PACE is the main England-and-Wales framework for policing that pairs police powers with safeguards for the public. The Police and Criminal Evidence Act 1984 works with its Codes of Practice. The Act supplies the statutory basis for the framework, while the Codes provide practical, subject-specific rules showing how its police powers and public safeguards operate in practice across the activities they cover.
The Codes address stop and search, arrest, detention, investigation, identification and interviewing. Section 24 supplies the grounds for arrest without warrant. Detention, identification and interviewing are separate subjects within the Codes, so their rules respond to those activities rather than becoming extra parts of the arrest test. A question about arrest therefore begins with section 24; a question about another covered activity turns to the rules for that subject.
The section 24 arrest test
For an arrest without a warrant under section 24, an officer needs reasonable grounds to suspect that the person is involved in an offence and reasonable grounds to believe that arrest is necessary. Both grounds must be present, and each must be reasonable before the arrest power is used.
The grounds do different work within the decision. Suspicion addresses the person’s possible involvement in an offence; necessity addresses why the arrest power needs to be used in the circumstances. One cannot substitute for the other. Together they make the decision depend on both a connection to the offence and a reason to use the arrest power.
Jurisdiction and the fairness safeguard
The PACE framework applies in England and Wales. Northern Ireland has a separate PACE Order, while arrest law in Scotland follows a different system. These differences make jurisdiction part of the legal answer before any particular power or safeguard is applied. The Act, Codes and section 24 rule discussed above should not be carried into the other UK jurisdictions as though their separate arrangements were identical.
PACE also gives courts a safeguard concerning prosecution evidence. A court may refuse that evidence when, after considering all the circumstances, including how the evidence was obtained, admitting it would adversely affect the fairness of proceedings so seriously that it ought not be admitted. The court makes that decision in the circumstances of the individual proceedings. The outcome depends on the section 78 fairness assessment; a PACE breach does not automatically exclude evidence or end the prosecution.
