It is not uncommon for police officers to justify the necessity of an arrest by reference to PACE s24(5)(e) - to allow the prompt and effective investigation of an offence or the conduct of the person in question. The case of R (TL) v Chief Constable of Surrey [2017] EWHC 129 (Admin) considers the extent to which this permits arrest for the purpose of imposing bail conditions and conducting a search.

The Claimant’s ex-partner told the police that the Claimant had raped her during their relationship. The investigating officer informed the Claimant that he wanted to interview him and that he should make no contact with his ex-partner. He agreed to both. Despite this, the investigating officer had already decided, even before having interviewed the ex-partner, that he would arrest the Claimant. On the Claimant's attending the police station, the investigating officer arrested him.

The judgment in this case is fairly long and worth reading in full. The main points of the decision are that Divisional Court stated:

- Multiple reasons which are individually ‘below the waterline’ of legality cannot amount to a lawful justification taken cumulatively [41]. It is not enough, therefore, for an arresting officer to reach for multiple reasons that could justify an arrest in the hope that the combined effect will amount to sufficient justification.

- In principle, the imposition of bail conditions may be necessary to bring about a prompt and effective investigation if there are reasonable grounds for believing that bail conditions are necessary to protect a witness from intimidation, which would or might render the investigation substantially less effective [52]. That is, however, different from the grounds in PACE s24(5)(d) - for the protection of a person, which needs separate consideration [60].

- The court left undecided whether, as a matter of principle, the police could rely on the reason of wanting to perform a PACE s18 search as a sole justification [71]. It was, however, sceptical. 

The facts of this case are instructive for police officers. They show how officers can easily fail to effect a lawful arrest by considering general terms instead of focussing on the specific circumstances concerned. As a brief summary:

- The officer could not rely upon the imposition of bail conditions to ground the lawfulness of the arrest where the Claimant had known for some time that he was under investigation for a sexual offence, was of good character, had breached no previous assurances and where there was no recorded urgency to arrest him. The decision to impose bail conditions had been on general policy grounds rather than the particular circumstances of the Claimant [54].

- The officer had no reasonable grounds for believing that it was necessary to arrest the Claimant in order to exercise powers of summary search pursuant to PACE s18. There has been such delays that it was not so urgent that a warrant under s8 could not reasonably have been obtained. The officer had not shown that the risk of destroying evidence arose in the short period during which a warrant could have been obtained. The officers should have applied for a search warrant pursuant to PACE s8 [73].

This is an important example of where police officers may have confused a power to do something with whether it would lawful to exercise such a power in the specific circumstances with which they were dealing. Officers must consider the necessity for arrest on the specific circumstances.