The Power of Arrest: The Legal Framework Under Section 24 PACE

The power of arrest is one of the most significant coercive powers available to law enforcement. An arrest represents a substantial interference with an individual's liberty and is therefore subject to both statutory safeguards and judicial scrutiny. Despite its importance, the legal framework governing arrest is frequently misunderstood.

In England and Wales, the principal power of arrest is contained in section 24 of the Police and Criminal Evidence Act 1984 ("PACE"), as amended by the Serious Organised Crime and Police Act 2005. The modern statutory framework seeks to balance the effective investigation and prevention of crime with the protection of individual rights and freedoms.

The Legal Test for Arrest

For an arrest to be lawful, a police officer must satisfy two separate statutory requirements.

First, the officer must have reasonable grounds for suspecting that the individual has committed, is committing, or is about to commit a criminal offence.

Secondly, the officer must reasonably believe that the arrest is necessary for one or more of the statutory purposes set out in section 24 PACE.

The existence of reasonable suspicion alone is insufficient. Both the suspicion requirement and  necessity requirements must be satisfied for an arrest to be lawful.

Reasonable Suspicion

Reasonable suspicion is a fundamental safeguard within criminal procedure. It requires an objective basis for the officer's suspicion, founded upon facts, intelligence, or information available at the time of the arrest. Mere intuition, assumption, or speculation will not ordinarily satisfy the statutory test.

The courts have consistently emphasised that reasonable suspicion is a lower threshold than proof or belief. Nevertheless, there must be objective material capable of justifying the officer's suspicion. Whether reasonable suspicion existed is assessed by reference to the information known to the arresting officer at the time the decision to arrest was made.

The Necessity Requirement

The necessity test is one of the most important protections against arbitrary arrest. Even where reasonable suspicion exists, an arrest will be unlawful unless the officer reasonably believes that it is necessary for one or more of the statutory purposes contained within section 24(5) PACE.

These purposes include:

• allowing the prompt and effective investigation of an offence
• preventing the suspect from causing physical injury
• preventing loss of or damage to property
• protecting a child or other vulnerable person
• preventing the suspect's disappearance before the investigation can take place; and
• establishing the suspect's name or address where these cannot readily be ascertained.

The introduction of the necessity requirement was intended to discourage unnecessary arrests and to ensure that less intrusive alternatives are considered whenever appropriate.

Information That Must Be Given

A lawful arrest requires more than mere statutory grounds.

Under section 28 PACE, the individual must be informed that they are under arrest and, as soon as reasonably practicable, of the grounds for the arrest unless this is impracticable because of the person's condition or behaviour. Failure to comply with these requirements may render the arrest unlawful.

Following arrest, the suspect will ordinarily be cautioned:

"You do not have to say anything, but it may harm your defence if you do not mention when questioned something which you later rely on in court. Anything you do say may be given in evidence."

The caution protects the suspect's right to silence while also explaining the potential evidential consequences of failing to mention matters later relied upon in their defence.

Arrest and Human Rights

The exercise of the power of arrest engages Article 5 of the European Convention on Human Rights, which protects the right to liberty and security of the person.

Any deprivation of liberty must therefore be lawful, necessary, proportionate, and carried out in accordance with a procedure prescribed by law.

The courts have consistently recognised that, although Parliament has granted police officers significant powers of arrest, those powers must not be exercised arbitrarily or disproportionately. An arrest that satisfies the statutory requirements may nevertheless be vulnerable to challenge if exercised in a manner incompatible with Convention rights.

Challenging the Lawfulness of an Arrest

The legality of an arrest may arise in both criminal and civil proceedings.

An unlawful arrest may affect:

• the admissibility of evidence
• the lawfulness of subsequent detention
• claims for false imprisonment
• claims for assault or battery; and
• proceedings under the Human Rights Act 1998.

The consequences of an unlawful arrest can therefore extend well beyond the criminal investigation itself.

Conclusion

The power of arrest remains an essential component of criminal investigation. However, it is not an unrestricted power. Before depriving an individual of their liberty, a police officer must have reasonable grounds for suspicion and must reasonably believe that arrest is necessary for one of the statutory purposes prescribed by Parliament.

The statutory framework reflects the principle that arrest should be a measure of necessity rather than convenience. As the courts continue to scrutinise the exercise of police powers, the principles of legality, necessity, proportionality, and respect for individual liberty remain central to modern criminal procedure.