Every police officer knows they must have a reasonable suspicion that a person has committed an offence in order to arrest them. But that is only half of what is required. The second element is that they must have a reasonable belief in the necessity for the person’s arrest. The recent decision of Commissioner of the Metropolitan Police v MR  EWHC 888 (QB) is one of a number of recent cases where appellate judgments have sought to tighten-up what the police must show in order to prove necessity.
In the instant case, a woman ‘A’ and her partner ‘MR’ had been in a relationship for fifteen months. A complained to the police about MR, who could not be traced save for a mobile telephone number. A police officer called MR on 11 January 2010, who then attended a police station for voluntary interview on 12 January 2010. Whilst at the police station and before being interviewed, MR was arrested on suspicion of harassment. He was interviewed, photographed, and had his fingerprints and DNA samples taken. After nearly seven hours, the police released him on conditional bail. He claimed that the arrest and consequent detention was unlawful and was subsequently successful in the county-court. The Comissioner appealed to the High Court.
Every police lawyer knows what to expect when they look at the justification for a person’s arrest on the relevant custody record. It is nearly always that arrest was necessary “to allow the prompt and effective investigation of the offence or of the conduct of the person in question.”
This is one of the six statutory grounds for an arrest’s necessity, at Police and Criminal Evidence Act 1984 (‘PACE’) s24(5). The other reasons are to enable the name or address of the person to be ascertained, to prevent the person causing or suffering physical injury/loss or damage to property / committing an offence against public decency/unlawfully obstructing the highway, to protect a child or vulnerable person and/or to prevent any prosecution being hindered by the person’s disappearance.
Whereas an officer need only have reasonable grounds for suspecting that the person has committed an offence, they require reasonable grounds for believing that arrest is necessary. Belief is higher than suspicion.
In the High Court, appeal, Thornton J reiterated, at , that it was for the courts to perform an objective review as to whether an arresting officer had reasonable grounds for believing that arrest was necessary. If, and only if, an officer had such reasonable grounds then they had a discretion to arrest. In stating this, judge relied on the case of Hayes v Chief Constable of Merseyside Police  EWCA Civ 911;  1 WLR 517. The relevant part of that case is at paragraph :
“…(1) the policeman must honestly believe that arrest is necessary, for one or more identified [PACE] section 24(5) reasons; and (2) his decision must be one which, objectively reviewed afterwards according to the information known to him at the time, is held to have been made on reasonable grounds…”
Thornton J repeated that the meaning of necessary was something more than “convenient” or “desirable” , relying on R (TL) v Chief Constable of Surrey Police  EWHC 129 (Admin);  1 WLR 2047 at , which stated:
“However, it should be emphasised that the underlying concept in section 24(5) is that of necessity. This cannot be envisaged as a synonym for “desirable” or “convenient”. For present purposes the issue may be formulated thus: should this court, in the exercise of its review function, conclude that an arrest was necessary to allow the prompt and effective investigation of this complaint?”
Thornton J was not satisfied that the arresting officer had objectively reasonable grounds for believing that MR’s arrest was necessary. The judgment (being an appellate decision) does not expressly set out all the evidence that arresting officer gave for having reasonable grounds – although the grounds are implied by their dismissal. These were at :
(i) MR had attended voluntarily for arrest and fairly swiftly after the police had contacted him;
(ii) There was no urgency to progress the investigation;
(iii) The need to establish MR’s identity did not justify arrest;
(iv) The possibility of applying bail conditions did not justify arrest;
(v) The obtaining or MR’s telephone did not justify arrest.
As to reasons (iii)-(v), Thornton J held that MR would have had to give his details for the purpose of a voluntary arrest in any event , that it was not necessary to apply bail conditions as the police officer could have given a harassment warning  and that text messages would have been on A’s phone, such that it was not necessary to seize MR’s .
It followed that the High Court upheld the finding that the arrest and consequent detention was unlawful.
In Hayes, the court considered the issue of arrest where a person attended voluntarily for interview, holding that it could be necessary depending on the facts. At :
“Whilst of course it may be that it is quite unnecessary to arrest a suspect who will voluntarily attend an interview, as it was with the schoolteacher in the Richardson case  2 Cr App R 1, it is not the case that a voluntary attendance is always as effective a form of investigation as interview after arrest.”
The judgment in Hayes went on to state that relevant factors could include the fact that a person had to be told that they could leave a voluntary arrest resulting in their interrupting the questioning, delaying further questioning as a subsequent arrest would them take time before the interview could recommence, there could be manipulation with witnesses, it might be necessary to seize a mobile telephone or it could be necessary to impose bail conditions.
The courts have been anxious to ensure that the police give proper consideration to the justification for arrest and its necessity, rather than merely relying on the catch-all “necessary for prompt and effective investigation” ground. Thornton J referred to these, citing Hanningfield v Chief Constable of Essex Police  EWHC 243 (QB);  1 WLR 3632, which itself held at  that although it was not for a judge to second-guess operational decisions of police officers, arrest would not be necessary where there was no rational basis for rejecting alternative procedures. For different reasons in R (TL) v Chief Constable of Surrey Police, the High Court held that an arresting officer did not have reasonable grounds to believe that arrest was necessary where he had relied on the need to obtain evidence by way of questioning. to prevent interference with the complainant and to perform a search.
It is difficult to extrapolate much from Thornton J’s judgment because it does not (as an appellate decision) repeat the detailed facts found at first instance – and where the trial was in the county court and, therefore, not reported or citable. The judge’s reasons for rejecting the grounds of establishing MR’s identity, applying bail conditions and searching the telephone will be intensely fact sensitive although, of course, the overall conclusions reached will, no doubt, be repackaged and argued in subsequent claims.
It is of interest that Thornton J suggested that MR’s arrest was potentially premature, insofar as it could have been done at a later point had MR not co-operated in interview or in provided his telephone, in contrast to that stated in Hayes. It may be that there was insufficient evidence to show that the arresting officer considered these possibilities and/or gave rational reasons for rejecting them, per Hanningfield.
All said, this is another reminder that police officers must give consideration to readily apparent reasons for not arresting and to explain why arrest was necessary. Given the many hundreds of arrests that take place, that is likely to be easier said by lawyers than done by front-line officers.