Authored By: Nafeesah Rahman
SOAS, University of London
Case Citation and Basic Information
Lewis-Ranwell (Respondent) v G4S Health Services (UK) Ltd and others (Appellants) [2026] UKSC 2. Supreme Court of the United Kingdom. Judgment delivered 21 January 2026. Bench: Lord Reed (President), Lord Hodge (Deputy President), Lord Lloyd-Jones, Lady Rose, Lady Simler. Judgment delivered by Lord Hodge and Lord Lloyd-Jones, with whom the remaining Justices agreed. Unanimous decision.
Introduction
Lewis-Ranwell [2026] UKSC 2 resolves a previously open question in English tort law: whether the illegality defence can bar a negligence claim where the claimant committed serious violence but was acquitted of murder by reason of insanity, holding no criminal conviction. Prior authority — most notably Henderson v Dorset Healthcare University NHS Foundation Trust [2020] UKSC 43 — had applied the defence only where a criminal conviction existed, albeit one reduced to manslaughter through diminished responsibility. The Supreme Court held that criminal conviction is not decisive, extending the Patel v Mirza [2016] UKSC 42 framework to this novel context. The Court further confirmed that Human Rights Act 1998 claims under Articles 3 and 8 ECHR are not barred by the common law defence, producing a two-tier remedy structure with significant implications for mental health litigation.
III. Facts of the Case
Alexander Lewis-Ranwell, aged 32, a diagnosed schizophrenic with a history of psychiatric intensive care, killed three elderly men — Mr Anthony Payne, Mr Richard Carter, and Mr Roger Carter — on 10 February 2019, during a psychotic episode in which he delusionally believed them to be paedophiles. In the days prior, he had twice been arrested and detained. During both periods of custody he behaved erratically, was seen by mental health professionals employed by the defendants, and on each occasion a formal assessment was discussed but not arranged before he was released on bail.
The defendants were G4S Health Services (UK) Limited (forensic medical services in custody), the Chief Constable of Devon and Cornwall Police, Devon Partnership NHS Trust (mental health assessments in the criminal justice system), and Devon County Council (emergency mental health team). Lewis-Ranwell was found not guilty of murder by reason of insanity under the Criminal Procedure (Insanity) Act 1964[1] and detained at Broadmoor Hospital under the Mental Health Act 1983.[2]
In February 2020, he brought civil proceedings in negligence and under the Human Rights Act 1998 [3], arguing that but for the defendants’ failures to arrange adequate assessments, he would have been hospitalised and would not have committed the killings. Pleaded heads of loss included compensation for compulsory detention, loss of earnings, loss of reputation, and an indemnity against claims by victims’ families. The Supreme Court proceeded on assumed facts, being a strike-out application[4]. Both the High Court and Court of Appeal (majority, Andrews LJ dissenting) rejected the strike-out, holding the defence inapplicable where the claimant did not know his acts were wrong. The defendants appealed. Critically, the Supreme Court proceeded on assumed facts, having emphasised that at the strike-out stage “it is necessary to proceed on the assumption that the claimant will make good at trial all the allegations in his pleaded case.”[5]
Legal Issues
Issue 1: Whether killings committed during a psychotic episode, resulting in a not guilty by reason of insanity verdict under the Criminal Procedure (Insanity) Act 1964, constitute “unlawful conduct” engaging the threshold for the illegality defence.
Issue 2: Whether the Patel v Mirza[6] framework as applied in Henderson[7] extends to cases without criminal conviction, such that absence of criminal responsibility is not decisive.
Issue 3: Whether the criminal law distinction between diminished responsibility and insanity should govern the availability of the illegality defence in civil proceedings.
Issue 4: Whether denial of the claim is proportionate applying the Patel v Mirza three-stage analysis on the assumed facts.
Issue 5: Whether the “narrow rule” in Gray v Thames Trains remains a distinct rule of law or has been subsumed into the Patel v Mirza framework of systemic coherence.
Arguments Presented
5.1 Appellants’ Arguments
Criminal conviction is not a prerequisite for ex turpi causa. The Patel v Mirza framework focuses on the coherence of the legal system, not criminal responsibility. Killing three people engages the most fundamental moral prohibition regardless of mental state. The insanity/diminished responsibility distinction is one of degree on a spectrum of mental illness severity. Allowing recovery would generate incoherence — a civil court compensating Lewis-Ranwell for a detention the criminal court itself ordered to protect the public, damaging public confidence in the legal system[8].
5.2 Respondent’s Arguments
The defence operates only where the claimant knew their conduct was unlawful. The insanity verdict under the M’Naghten Rules[9] is the law’s own recognition that such knowledge was absent. It is internally contradictory for civil law to simultaneously treat the claimant as acquitted and bar his claim on the basis of that conduct. Compensating a mentally ill person for the consequences of the defendants’ own negligent failure raises no affront to the integrity of the legal system under Patel v Mirza.
Court’s Reasoning and Analysis
The Court addressed two questions: whether the conduct crossed the threshold to engage the defence, and whether the defence should apply on the facts.
On the threshold, criminal conviction is not required[10]. Killing three men without lawful justification “breaches the most fundamental moral rule in our society,” remaining true “even when the person bears no criminal responsibility.[11]” The Court rejected the Court of Appeal’s approach for three reasons: the law of insanity is archaic and an unsatisfactory determinant of civil policy[12]; civil law need not replicate the criminal law’s sharp dividing lines; and the difference between diminished responsibility and insanity is a difference of degree that “has no bearing on the coherence of the law which is of central importance.”[13]
Applying the Patel v Mirza three-stage framework: Limb (a) — Purpose of the prohibition transgressed: The Court identified the transgressed prohibition as the fundamental rule against unlawful killing, whose purposes include preservation of life, deterrence, public condemnation, and acknowledgment of harm to victims. These purposes apply with equal force to a claimant acquitted on grounds of insanity[14]. Allowing recovery would generate a stark inconsistency: a civil court would compensate the claimant for a hospital detention that the criminal court itself ordered to protect the public — an outcome that would undermine public confidence in the legal system.[15]
Limb (b) — Other relevant public policies: The Court acknowledged the general public interest in courts adjudicating civil wrongs and accepted that litigation might expose systemic failures. However, it held that inquests and public inquiries are better suited to scrutinising such failures[16]. The policy considerations favouring maintenance of the legal system’s integrity greatly outweighed those favouring the claim.
Limb (c) — Proportionality: Proportionality requires close engagement with the specific facts of the case. The killing of three elderly men in their own homes was of “the utmost seriousness,” and crucially, those acts were central to every head of loss claimed — the detention-related losses fell within Lord Hoffmann’s narrower rule in Gray v Thames Trains Ltd[17], and the indemnity claim required the claimant to rely directly on his own wrongful acts. Denial of the claim was therefore a proportionate response.[18] The Court clarified the relationship between the “narrow rule” in Gray (which bars recovery for losses flowing from a sentence or detention imposed by a criminal court) and the Patel framework. It held that Gray is essentially a specific application of the broader principle of coherence: it would be “self-contradictory” for the law to simultaneously detain a person for the public’s safety and then require a different arm of the state to compensate that person for the detention.
This “HRA carve-out” is rooted in the constitutional principle of statutory priority. Under Section 6 of the Human Rights Act 1998[19], it is unlawful for a public authority to act in a way which is incompatible with a Convention right. The Court reasoned that a common law rule of public policy, such as ex turpi causa, cannot be invoked to bypass a court’s statutory duty to determine whether a public authority has breached Articles 3 or 8.
VII. Judgment and Ratio Decidendi
The Supreme Court unanimously allowed the appeal. Lewis-Ranwell is barred from recovering in negligence for any pleaded head of loss. HRA claims proceed.
Ratio decidendi: The illegality defence operates by reference to the nature and seriousness of the claimant’s conduct, not the existence of a criminal conviction; an insanity acquittal does not preclude the defence where the Patel v Mirza three-stage analysis confirms that denial serves the purpose of the prohibition transgressed, is consistent with other public policies, and is proportionate to the gravity and centrality of the unlawful conduct.
Obiter: The Court noted illegality may in appropriate cases exclude particular heads of loss while permitting others, and that the indemnity claim was separately objectionable as requiring direct reliance on wrongful acts.
VIII. Critical Analysis
8.1 Significance
Lewis-Ranwell definitively resolves that the illegality defence does not require criminal conviction, marking the most significant development since Henderson and Patel v Mirza. The civil law is unconstrained by the criminal law’s categorisation of responsibility, and the Patel v Mirza framework now operates as the universal template across all civil illegality claims.
8.2 Implications and Impact
For mental health providers, the ruling reduces tort liability precisely where negligent care has the most catastrophic consequences, raising legitimate concerns about perverse incentives. As the Law Commission observed in its 2010 Report, the harshness of a defence denying all recovery sits uneasily with tort law’s compensatory function where the defendant’s own wrong materially contributed to the harm[20]. The HRA track survives but is narrowed: damages are typically modest, and positive obligation claims under Articles 3 and 8 face demanding thresholds derived from Osman v United Kingdom[21]. Whether this adequately vindicates the rights of mentally ill claimants failed by the state remains an open question for Parliament.
8.3 Critical Evaluation
The most searching criticism is the moral culpability problem. The insanity verdict is the common law’s own recognition of the complete absence of criminal responsibility. Applying ex turpi causa against that same person produces a fundamental contradiction: the law simultaneously declares the claimant not criminally responsible and bars his civil claim on the basis of that conduct. As Goudkamp argues, the defence sits most coherently where the claimant made a morally autonomous choice to act unlawfully[22]; that foundation is entirely absent where acts were committed during a psychotic episode. A further objection is that the Patel v Mirza framework was developed for consensual commercial illegality and implicitly assumes a rational autonomous agent — an assumption that collapses where the claimant did not know their act was wrong. The most searching criticism is the moral culpability problem.
The Court’s position nonetheless has systemic logic: making the defence contingent on conviction would produce the anomaly that defendants bear full civil liability precisely where the claimant’s mental illness was too severe for prosecution. The HRA carve-out reflects judicial discomfort with total denial of remedy but remains underarticulated — the Court does not engage with the Osman positive obligation jurisprudence giving those surviving claims their substantive content.
The survival of the HRA claims creates a curious “two-tier” liability landscape. While the common law bars recovery for the “loss of liberty” or “damage to reputation” resulting from the killings, the state remains accountable for the underlying systemic failure to protect life or prevent ill-treatment. This suggests that while the claimant cannot profit from his “wrong,” the state cannot use that same “wrong” to shield its own human rights obligations from judicial scrutiny.
Conclusion
Lewis-Ranwell v G4S Health Services (UK) Ltd [2026] UKSC 2 marks a decisive and controversial extension of the illegality defence. By holding that the defence operates by reference to the nature of the act rather than the legal status of the actor, the Supreme Court has confirmed that a claimant acquitted on grounds of insanity may nonetheless be barred from recovering in negligence for the consequences of his own acts. The central takeaway is that the Patel v Mirza framework is now the definitive template for illegality across civil claims, unconstrained by the criminal law’s categorisation of responsibility. The lasting significance of the decision lies in its reframing of the insanity/diminished responsibility divide as a difference of degree rather than a principled distinction. This will shape future mental health litigation and any case where a claimant’s serious prior conduct is implicated in the loss claimed. Unresolved questions remain: the threshold of seriousness below homicide, the adequacy of the HRA remedy as a substitute for tort recovery, and whether legislative reform to introduce a mental incapacity exception to the illegality defence is now required. These questions will define the next chapter of this developing area of law. Finally, the decision does not signal an automatic victory for the defendants on the surviving HRA claims. While the illegality hurdle is cleared, the claimant must still navigate the “high threshold” of proving a positive obligation breach under the Osman framework. The Supreme Court has defined the boundaries of the defence, but the factual battle regarding medical standard of care and causation remains for the trial judge.
Bibliography
Table of Cases
UK Cases
Gray v Thames Trains Ltd [2009] UKHL 33, [2009] AC 1339
Henderson v Dorset Healthcare University NHS Foundation Trust [2020] UKSC 43, [2021] AC 563
Lewis-Ranwell v G4S Health Services (UK) Ltd [2026] UKSC 2
M’Naghten’s Case (1843) 10 Cl & Fin 200, 8 ER 718
Patel v Mirza [2016] UKSC 42, [2017] AC 467
European Cases
Osman v United Kingdom (1998) 29 EHRR 245
Table of Legislation
UK Statutes
Criminal Procedure (Insanity) Act 1964
Human Rights Act 1998
Mental Health Act 1983
Statutory Instruments & Treaties
Convention for the Protection of Human Rights and Fundamental Freedoms (European Convention on Human Rights, as amended)
Secondary Sources
Books
Goudkamp J, Tort Law Defences (Hart Publishing 2013)
Reports
Law Commission, The Illegality Defence (Law Com No 320, 2010)
[1] Criminal Procedure (Insanity) Act 1964, s 2.
[2] Mental Health Act 1983, ss 37, 41.
[3] Human Rights Act 1998
[4] Lewis-Ranwell [2026] UKSC 2, para 2.
[5] Lewis-Ranwell (Respondent) v G4S Health Services (UK) Ltd and others (Appellants) [2026] UKSC 2, para 2.
[6] Patel v Mirza [2016] UKSC 42; [2017] AC 467.
[7] Henderson v Dorset Healthcare University NHS Foundation Trust [2020] UKSC 43; [2021] AC 563
[8] Patel v Mirza [2016] UKSC 42; [2017] AC 467, [109] (Lord Toulson).
[9] M’Naghten’s Case (1843) 10 Cl & Fin 200; 8 ER 718.
[10] Lewis-Ranwell [2026] UKSC 2, paras 113–114.
[11] ibid, para 134.
[12] ibid, para 123.
[13] ibid, para 127.
[14] ibid, para 142.
[15] ibid, paras 144–151.
[16] ibid, para 156.
[17] Gray v Thames Trains Ltd [2009] UKHL 33; [2009] AC 1339; Lewis-Ranwell [2026] UKSC 2, para 146.
[18] n10, para 162.
[19] N3 S.6.
[20] Law Commission, The Illegality Defence (Law Com No 320, 2010) paras 2.1–2.5.
[21] Osman v United Kingdom (1998) 29 EHRR 245.
[22] James Goudkamp, Tort Law Defences (Hart Publishing 2013) ch 7.
