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Lexis+ AI
Emelia Bezant-Gahan

Associate, Weightmans

Necessity to arrest

Necessity to arrest


Emelia Bezant-Gahan analyses the developing case law around 'necessity to arrest' – which has a high evidential burden and is highly fact-sensitive.

Where a police officer arrests an individual without a warrant, they are required to follow certain conditions set out in the Police and Criminal Evidence Act 1984 (PACE) at s24 for it to be deemed a lawful arrest. The first requirement is for the officer to have reasonable grounds, in their own mind at the time of the arrest, to suspect that the individual has committed, or was about to commit, the offence for which they are being arrested (s24 (2) PACE). The leading authorities in this area place the evidential hurdle for meeting this requirement fairly low.

However, the second requirement set out at s24 (4) and (5) PACE is a much higher evidential burden and states that the arrest must be deemed necessary for one of the following reasons:

(a) to enable the name of the person in question to be ascertained (in the case where the constable does not know, and cannot readily ascertain, the person's name, or has reasonable grounds for doubting whether a name given by the person as his name is his real name);(b) correspondingly as regards the person's address; (c) to prevent the person in question—(i) causing physical injury to himself or any other person; (ii) suffering physical injury;(iii) causing loss of or damage to property; (iv) committing an offence against public decency (subject to subsection (6)); or (v) causing an unlawful obstruction of the highway; (d) to protect a child or other vulnerable person from the person in question; (e) to allow the prompt and effective investigation of the offence or of the conduct of the person in question; (f) to prevent any prosecution for the offence from being hindered by the disappearance of the person in question

This requirement has been developed and defined through case law with some fascinating decisions.


Previous decisions

The high court case of Richardson v Chief Constable of the West Midlands [2011] EWHC 773 (QB) considered the necessity to arrest a teacher, who had been arrested and detained after voluntarily attending a police station following allegations that he had assaulted a pupil. In that case, it was found that the arresting officer failed to show that she had reasonable grounds for believing that his arrest was necessary, as required by s.24(4) of PACE. The court held that there was simply no evidence as to whether, and if so why, the arresting officer had considered it necessary to arrest the claimant.

The only evidence of the reasons for arrest were that at the first police station the claimant had been told that if he did not accept a local resolution he would be arrested, and the entry within the custody record of the statutory reason for arrest which was within s.24(5)(e) (set out above). It could be inferred from the custody officer's note that he had considered the arrest to be appropriate for the reason set out in the PACE codes of practice Code C para.3.21, but there was no evidence that he had taken into account any other reasons why the claimant’s arrest had been necessary.

Following on from Richardson was the court of appeal authority Hayes v Chief Constable of Merseyside [2011] EWCA Civ 911. In this case, the court re-stated the correct test for exercising the statutory power of arrest. The claimant/appellant had alleged that his arrest and detention was not lawful because the arresting officer had not considered an alternative to arrest and could not therefore show that his arrest was necessary. He also alleged that because his reported victim withdrew his complaint his detention was unlawful from that point onwards.

The court of appeal dismissed his appeal. They found that it was common ground for the police to justify an arrest. In the instant case the constable therefore had to show two things: first, under PACE s.24(2), that he had reasonable grounds for suspecting that an offence had been committed and that H was guilty of it; and secondly, that he had reasonable grounds for believing that it was necessary to arrest the appellant to allow the prompt and effective investigation of the offence, as per s.24(4) and s.24(5)(e). The parties agreed that the first condition had been met.

With regard to the second they held that a police officer ought to apply his mind to alternatives short of arrest, and if he did not do so he was open to challenge. Code of Practice G provided a sensible warning to that effect. But the challenge was not one which required the officer's decision to be subjected to a full-blown public law reasons challenge. It was one which required it to be shown that, on the information known to the officer, he had reasonable grounds for believing arrest to be necessary, for an identified s.24(5) reason.

That conclusion best represented the balance which the law had to strike between practicable policing and the preservation of the liberty of the subject. To require a policeman to pass through particular thought processes each time he considered an arrest, in all circumstances no matter what danger might attend the decision, and to subject that decision to the test of whether he had considered every material matter and excluded every immaterial matter, was to impose an unrealistic and unattainable burden.

The liberty of the subject was amply safeguarded if the rule was the following: (a) that the constable actually believed that arrest was necessary, and for a reason in s.24(5) and (b) that belief, on the information known to him at the time, was objectively reasonable.

Assuming that the judge had applied that two-stage test, his conclusion that the appellant's arrest was lawful was unassailable (paras 21, 39-42). (3) Under s.34(2)(a) the custody sergeant was under a duty to release H if at any time he became aware that the grounds for detention had ceased to apply. It was not arguable that there were no longer grounds to detain the appellant for interview simply because the purported victim had said that he wished to withdraw his complaint for a variety of reasons that may arise during an investigation.

The later and lower court decision of Commissioner of Police of the Metropolis v MR [2019] EWHC 888 (QB) in the high court held that the test of necessity was a “high bar”. In MR, the claimant had attended a police station for a voluntary interview and was arrested on suspicion of harassment. The court found that there had been no objective necessity to arrest an individual who had voluntarily attended a police station in respect of an allegation of harassment, notwithstanding the fact that the low threshold required for the arresting officer to have reasonable grounds to suspect the commission of an offence had been crossed.

There was an absence of any record of the reasons for the arrest as required by PACE Code G in this matter and the court was not convinced by submissions made by the defendant that the officers were concerned that a voluntary interview would alert the claimant to the fact he was a person of interest. The court referred to Hayes and confirmed that an officer who had given no thought to alternatives to arrest ran the risk of being found to have had objectively no reasonable grounds for the belief that arrest was necessary. They further found that the obvious alternative to arrest had been to interview the respondent, establish his identity and obtain his phone.

A 2022 decision in the High Court ST v Chief Constable of Nottinghamshire [2022] EWHC 1280 (QB) allowed an appeal against a judge's dismissal of a false imprisonment claim in respect of a 14-year-old boy who had been arrested at 5.30am in his family home and detained for six hours in an adult cell. It was held that the arresting officers had not had objectively reasonable grounds to believe that the circumstances made it necessary to arrest the boy in that manner. They had failed to take his age into consideration or to consider other reasonable options.


Recent developments

A recent high court case DE v West Midlands [2023] EWHC 146 (KB) saw the chief constable of West Midlands Police successfully defend an appeal to the High Court following the dismissal of the appellant’s false imprisonment claim at trial. Mrs Justice Hill upheld the initial decision judge’s findings that in the circumstances of the case it was justified to rely on the s24(5)(e) PACE “prompt and effective investigation” criterion where the arresting officer’s sole reason for believing the arrest to be necessary was an intention to impose bail conditions.

The core issue for the court was whether the judge had erred in their finding, in accordance with the well-established test in Hayes. The court, Mrs Justice Hill presiding, rejected all four of the appellant’s grounds.

The appellant had sought to argue that there had not been sufficient consideration, in the arresting officer’s evidence, of the alternative to arrest requirement. However, it was held that a brief or summary rejection of a non-arrest option is sufficient to meet the “cursory consideration” element of the two-stage Hayes test and that this had been established by the arresting officer.

The arresting officer had admitted that there was no urgency to the arrest. However, the officer had not argued that he considered the arrest necessary for a “prompt” investigation under PACE, section 24(5)(a), but rather an “effective” one under the same section. Finally, the appellant argued that this case was comparable to several other necessity cases in which it was found s24 of PACE was not satisfied.

The court was not persuaded by the usefulness of comparisons with previous cases (that could be distinguished on the facts) relied upon by the claimant as all decisions on this point [necessity to arrest] will be highly fact-specific. Indeed, the court found that the factual context was fundamentally different in many of the cases cited. Ground 1 of the appeal was therefore rejected, confirming that the judge had approached the task of determining the second limb of the Hayes test correctly. In Mrs Justice Hill’s judgment, objectively reviewed, according to the information known to him at the time, the arresting officer’s belief that it was necessary to arrest the appellant was based on reasonable grounds.

Regarding the second ground of appeal, the appellant asserted that the first instance judge was wrong in law to find that purely speculative grounds for believing that bail conditions might be necessary could satisfy the necessity criteria through section 24(5)(e). Mrs Justice Hill concluded that she could see no evidence the judge had made such a finding. The parties had agreed that bail conditions can, in principle, satisfy section 24(5)(e), depending on the facts of the particular case.

The remaining submissions under Ground (2) related to the evidence rather than the law, specifically the wording in the arresting officer’s MG11 that stated the arrest was “necessary in order to carry out a prompt and effective investigation of the matter and to enforce bail conditions should they be required”. It was argued that the final words there evidenced that the issue of bail conditions was still speculative, as was the potential for the appellant to contact witnesses after his arrest. This was in essence a re-formulation of Ground 1, and it was noted by the court that the first instance judge had specifically addressed this in the context of risk.

While the arresting officer’s assessment of risk was speculative, the main issue is whether there was a tangible risk rather than speculation without foundation. The respondent had argued at trial that the arresting officer’s risk, while speculative, was nevertheless made with a proper foundation. Mrs Justice Hill agreed and as such Ground 2 was dismissed. The third and fourth grounds of the appeal connected to a delay in the claimant’s release and a dispute on a finding of fact were also dismissed.



Necessity to arrest is quite rightly a very high evidential burden. A decision to arrest must be taken seriously and with consideration to alternatives. Necessity is often cited in civil claims arising out of arrests for harassment, with claimants suggesting that a voluntary interview would have been more appropriate. It will remain vital that officers continue to consider the alternatives and the suitability of non-arrest options, but it is a helpful reminder for practitioners and forces that a cursory consideration, in the form of summary rejection, can be sufficient to meet this burden upon officers set out in Hayes.

The recent case of DE is also a valuable insight into when the court will find that it is reasonable to rely on the s24(5)(e) PACE “prompt and effective investigation” criterion, where the arresting officer’s sole reason for believing the arrest to be necessary is an intention to impose bail conditions. It is the circumstance in many police investigations where there is a concern that the suspect may contact the complainant to intimidate, and this would clearly undermine an “effective” investigation.

Police law practitioners will no doubt welcome the high court decision in DE but as with all previous judgments in this area, the evidential burden for necessity to arrest remains high and the decisions remain highly fact-specific.

Emelia Bezant-Gahan is an associate at Weightmans.



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