AB v Chief Constable of North Wales Police [2026] EWCC 40

3rd July 2026

Self-harm, PAVA spray and proportionality in custody:

This county court decision of HH Judge W Owen on the use of PAVA incapacitant spray against a self-harming detainee provides a useful illustration of how the principles of necessity and proportionality apply in the custody context, and offers guidance on the assessment of damages in trespass-only claims against the police. The key take home point: Safeguarding does not trump proportionality. A legitimate safeguarding objective does not displace the proportionality requirement. The chosen tactic will be tested against realistic alternatives and the detainee’s vulnerability within the cell environment. Forces may wish to reinforce de-escalation and mental health training and review guidance on incapacitant use in custody. Sam was instructed by Donoghue Solicitors (a specialist actions against the police firm).

Core facts: The Claimant, a detainee with mental health difficulties, who had self-strangulated with clothing as a ligature just ten minutes prior, began striking his head against the wall in his custody cell. The custody sergeant opened the cell hatch for 9 seconds, shouting “hey fella”, before entering the cell and deploying PAVA spray at near immediate range to stop the behaviour.

The Central liability question: Whether that use of force was necessary and proportionate to prevent self-harm in a custodial setting (as distinct from force to protect officers or third parties).

Pleading posture: The claim was confined to trespass to the person (assault/battery)as limitation for personal injury and Human Rights Act claims had expired by the time of instruction; no medical evidence was relied upon and short-lived effects were conceded.

Outcome on liability: The court found the force unlawful. Notwithstanding the legitimate aim of preventing self-harm, deploying PAVA in the enclosed custody environment was not a proportionate response on the facts (and indeed “wholly unreasonable” in the setting of a self-harming and vulnerable detainee in acute mental distress). The Court awarded basic and aggravated damages as a rolled up lump sum (counsel having agreed that this approach was permissible).

The legal framework: necessity and proportionality where the risk is of self-harm

Statutory and common law tests: Force must be reasonable under section 117 of the Police and Criminal Evidence Act 1984 and section 3 of the Criminal Law Act 1967 in order to be lawful. Both statutory and common law justification were pleaded in the defence, both of which turn on necessity and reasonableness judged against the circumstances as the officer honestly believed them to be.

Co-existing custody specific duties: In custody, the above principles co-exist with a force’s operational duty of care and safeguarding obligations towards detainees; a higher standard is necessarily mandated when the force knows of a risk of self-harm (or ought to have). Where the threat is one of detainee’s own self-harm, necessity demands careful attention to immediacy, seriousness and available alternatives. Proportionality mandates the least intrusive effective means, with heightened scrutiny of enclosed-cell deployment, foreseeable chemical effects and mental health presentation.
Technique scrutiny: A court will examine not only whether intervention was justified in principle, but whether the chosen tactic—here, PAVA—was proportionate given risks, space constraints and the availability of other measures (particularly when used at closer to the recommended minimum range of 1 metre when such use risks retinal detachment injury).
Operational realism reminder: As per Turner J in Goodenough & Anor v Thames Valley Police [2020] EWHC 695 (QB) at para [45]: “The Court must take care not to judge the actions of the officers by unrealistic standards of detached reflection and retrospective analysis.” Operational realism is particularly important in the context of a custody suite with volatile detainees and ongoing self-harm. But Turner J’s test simply underscores that the officer’s honest perception at the time forms part of the analysis; it does not, however, displace the requirement that the force used be objectively necessary and proportionate in the circumstances.
The thrust of the Defence case: the Defendant heavily relied upon the concept of ‘operational realism’ at trial. But the particular setting of this case, including AB’s very recent act of self-strangulation by ligature – and its successful prevention by custody officers who showed AB care and compassion – did not justify the absence of any effective communication from the custody sergeant before he deployed the spray, which could not be explained away by ‘operational realism’ (reasonableness of course being the Defendant’s burden to discharge).

Objective vs subjective assessment: reconciling honest belief with reasonableness

- Subjective element—what the officer believed: The starting point is the officer’s honest appraisal of the circumstances, including the perceived immediacy and gravity of the self-harm risk. The common law frames necessity and reasonableness “judged against the circumstances as the officer honestly believed them to be.” It is the Defendant’s burden to discharge the subjective element.
- Objective element—what the law requires: Even accepting that honest belief, the court then asks whether the force used was reasonable and proportionate in those circumstances. If not, then the use of force is unlawful. In custody, proportionality is narrowed by detention in a confined cell and the vulnerability of detainees: the least intrusive effective means are required, and chemical agents in confined spaces will attract close scrutiny.

Distinct limbs of objectivity and subjectivity: in the recent authority of Afriyie v Commissioner of Police for the City of London [2024] EWCA Civ 1269 (where Donoghue Solicitors also acted for Mr Afriyie) the first instance Judge fell into error by conflating the subjective and objective components. The effect of a court inferring objective reasonableness from an officer’s subjectively held belief is an abstract and unreliable a self-fulfilling prophecy of reasonableness. The Court must stand back and assess the objective component independently of an officer’s belief even when sincerely held.

Application of the principles to the evidence in AB: The Court accepted the custody sergeant’s evidence that he sincerely believed his use of force to be necessary to protect himself and AB. But any legitimate safeguarding aim did not suffice where the specific tactic—PAVA in an enclosed cell at near immediate range —was not, on objective analysis, the least intrusive effective response given other realistic alternatives, and found the force unlawful.

Proportionality in custody: alternatives and operational judgment

Alternatives must be evidenced: In such cases the Court will test proportionality against practical options such as verbal de-escalation, observation with prompt cell entry by trained staff, soft protective equipment, controlled physical restraint, or moving the detainee to a safer environment. The court will expect clear, contemporaneous reasoning for why spray was necessary at the precise moment used, and why less intrusive options were inadequate—especially where mental ill-health is evident.
Technique selection is fact-sensitive: Cell dynamics, the detainee’s vulnerability, the officer’s options and the immediacy of the risk typically drive both liability and quantum. The choice to use CS/PAVA in custody requires particular justification because of dispersion characteristics, after-effects and the confined setting.

Evidence: the premium on CCTV/BWV and medical proof

Objective recordings are often determinative: In any such claim good-quality CCTV and body-worn video can establish sequence, duration, available alternatives, demeanour and the confined nature of the setting. Records of distance, number of bursts, ventilation, decontamination, access to water and aftercare are probative on proportionality and aggravation.
Documentation and healthcare evidence: Complete force forms, contemporaneous custody records reflecting dynamic risk assessments and tactical options, and aftercare documentation are essential. Claimants should also secure medical notes, custody healthcare records and timely witness statements on immediate and short-term effects.
The evidence in AB: it was contended on behalf of AB that the evidence spoke for itself. Counsel for the Defendant cautioned the Court against overreliance on the CCTV footage in isolation and directed the Court to scrutinise the surrounding circumstances. Ultimately these were insufficient to justify the reasonableness of the force.

PAVA/CS spray in the authorities: comparisons and cautious analogies

Varied fact patterns and limited quantum guidance: Reported decisions vary; some do not identify spray type and public summaries can be thin on quantum. Courts distinguish brief exposure with transient effects from cases with lasting injury or aggravating conduct; medical evidence significantly influences quantum.
Fact-sensitivity and product differences: Where earlier authorities do not specify CS or PAVA, analogies must be cautious given differences in mechanism, dispersion and after-effects. Proportionality remains intensely fact-sensitive, with custody-specific constraints often decisive.

Quantum—the jurisprudential basis of the award of £2,500

Pleading confined to trespass: The court’s focus was on wrongful application of force, not medically evidenced injury or Human Rights Act violations.
No medical report; short-lived effects conceded: This constrained the compensatory element that clinically substantiated sequelae might otherwise support.
Single combined award for basic and aggravated damages: The court folded aggravating features into one figure, avoiding separate head-by-head assessment. The Thompson guidance includes that an award of aggravated damages being more than 3x than that of the compensatory component will be ‘unusual’. But given the confined causes of action and short-term effect of the spray, a ‘usual’ Thompson approach to the assessment of aggravated damages might have under compensated the Claimant. Claimant counsel made analogous reference to an award of basic damages for application of handcuffs usually being at least several hundred pounds, with an application of PAVA spray plainly being a more culpable trespass.
The £2,500 award principally vindicates the trespass with a measured uplift for aggravating features, rather than compensating sustained injury or imposing a punitive element. Whilst awarded on a ‘lump sum’ basis, a notional application of the ‘usual’ Thompson approach would be basic damages of £625 before the application of aggravated damages (£625 + 3* £625). Exemplary damages were refused.

Conclusion

AB v Chief Constable of North Wales Police [2026] EWCC 40 confirms that preventing a detainee from self-harming does not, of itself, justify the use of incapacitant spray in custody. Necessity and proportionality remain the touchstones: the officer’s honest belief is considered, but the force must still be objectively reasonable and the least intrusive effective means in the circumstances. Where alternatives exist, the use of chemical force in an enclosed environment will be closely scrutinised. The £2,500 combined award reflects the trespass-only pleading, the absence of medical evidence and the lump-sum approach, and is best understood as measured vindication rather than compensation for sustained injury or a punitive sanction.

Key points

Necessity and proportionality govern force used to prevent self-harm in custody.
Officer’s honest belief is assessed, but objective reasonableness/proportionality ultimately controls.
PAVA/CS in cells demands strong justification; alternatives must be evidenced before deployment.
Trespass-only claim, no medical report and short-lived effects aligned with a £2,500 combined basic/aggravated award; exemplary damages were refused.
CCTV/BWV, detailed custody records and aftercare evidence are central to liability and quantum.

About the author

Sam Aynsley

Sam is a barrister at Nine Chambers. He has a multi-faceted civil practice split between Tort — including Personal Injury, Clinical Negligence and Actions Against the Police — and Business and Property. He acted for the Claimant in AB v Chief Constable of North Wales Police.

For enquiries about instructing Sam, please contact the clerking team at Nine Chambers.