Armstrong v Chief Constable of West Yorkshire Police

Reasonable suspicion for arrest has a low threshold. It does not require prima facie evidence and may rest on apparently reliable hearsay. The question is objective, but is assessed by reference to the information known to the officer making the arrest decision, including its source, context and the whole surrounding circumstances.

The quality and completeness of an investigation may be relevant, but there is no general requirement that officers complete further enquiries before suspicion can crystallise. The court must assess the cumulative force of the available information, rather than discount each item in isolation. In urgent investigations, an imperfect or traumatised eyewitness description does not necessarily prevent a lawful arrest where other material links the suspect to the offence.

Following a grave sexual assault in Leeds, police arrested Mr Armstrong on suspicion of rape. The decision was based on information from a police officer and her adult daughter that he generally matched the offender’s description, wore similar distinctive dark clothing, lived near the attack, frequented city-centre clubs and preferred to be called Daniel.

Mr Armstrong was later exonerated. He brought claims including false arrest and false imprisonment. The Leeds County Court held that the officers genuinely suspected him but lacked reasonable grounds because the investigation had not been sufficiently thorough and aspects of the description did not match.

The Chief Constable appealed. The central issue was whether, on the information known to the police and the surrounding circumstances at the time, there were objectively reasonable grounds to suspect Mr Armstrong.

1. Appeal allowed. The Recorder applied the test for reasonable suspicion too strictly and with hindsight. The court substituted judgment for Mr Armstrong in the agreed sum of £50 for the separate battery claim.
2. Reasonable suspicion is a preliminary investigative standard. It does not require evidence capable of establishing a prima facie case and may be founded on hearsay. The objective inquiry concerns the information in the mind of the officer who made the arrest decision, assessed in light of its source, context and the whole surrounding circumstances: [1970] AC 942; [1997] AC 286; [2008] EWCA Civ 1237.
3. The Recorder wrongly treated a reasonably thorough pre-arrest investigation as a necessary condition of lawful suspicion. The thoroughness of enquiries may be relevant, and in some circumstances further enquiries may be needed, but an arrest may lawfully occur at an early stage. The violent rape investigation was urgent: the police had to protect the public, preserve evidence and avoid alerting a possible offender.
4. The Recorder also erred by examining each item of information separately. The proper approach was to consider their cumulative effect. The information came from an apparently reliable trained police officer and her adult daughter, both of whom knew Mr Armstrong. It linked him to the offender’s name, clothing, locality and habits.
5. The differences between Mr Armstrong’s appearance and the victim’s description did not make the arrest unreasonable. The police could properly allow for the fallibility of a description given by a drunk, terrified and traumatised victim of a night-time attack. The arresting officers were not required to abandon the arrest on seeing him.
6. Lady Justice Arden agreed, adding that the Recorder’s overcompartmentalised treatment of the evidence was a misdirection. A lawful arrest justified the interference with liberty under Article 5 of the European Convention on Human Rights.

• Court of Appeal (Civil Division) Allowed the Chief Constable’s appeal and substituted judgment for the claimant in the agreed sum of £50 for a separate battery.
• Leeds County Court (Mr Recorder Myerson QC) On 8 May 2008, held that the police lacked reasonable grounds to arrest the claimant on suspicion of rape.