Henderson v Dorset NHS Trust: seven Justices and the fifth commandment

Ecila Henderson was being treated by Dorset for serious psychiatric illness. During a period in which she had been negligently released from its care her condition caused a foreseeable a loss of control in which she killed her mother. She was convicted of manslaughter and the Supreme Court had to decide if she could recover damages in tort flowing from the Trust’s failure properly to care for her.

Henderson is the latest in a line of cases over the last few years in which the Supreme Court has had to deal with a clear breach of duty by a defendant and a claimant acting illegally. In one of the lead cases, Gray v Thames Trains, it refused compensation to a man who had suffered such serious PTSD in the Ladbroke Grove train crash that it caused him to kill a driver in a road rage incident some time afterwards.

After Gray the Supreme Court had further refined the illegality defence – often cited in Latin as ex turpi causa non oritur actio, ie a wrongful act shall not ground a claim – in a range of contract and tort settings. The essence of it is, following Patel v Mirza in 2016, that a policy-based approach should be taken, entailing an inquiry into whether allowing the claim would lead to inconsistency that would damage the integrity of the legal system.

The answer to this question might appear simple on the bare facts as described above and indeed it might be thought to follow from the fifth Old Testament commandment: Thou shalt not kill. However, it should be borne in mind that Ms Henderson was at all times owed a duty of care by Dorset and that that was breached which, foreseeably (and with horrific consequences), caused her losses in this case (mainly her deprivation of liberty following the manslaughter conviction and forfeiture from inheriting her mother’s estate). Therefore the tort was complete – duty, breach, causation and loss all being present – so the key question was whether policy considerations should bar the exercise of her rights?

The seven Justices were unanimous that her claim should be barred, affirming the earlier decisions of the Court of Appeal and the High Court in this case and re-emphasising the approach set down in Patel. Lord Hamblen gave the only judgment and directly approved Lord Toulson’s formulation in Patel of the correct approach to illegality: “The essential rationale of the illegality doctrine is that it would be contrary to the public interest to enforce a claim if to do so would be harmful to the integrity of the legal system … Within that framework, various factors may be relevant, but it would be a mistake to suggest that the court is free to decide a case in an undisciplined way. The public interest is best served by a principled and transparent assessment…”

Lord Hamblen added that although the underlying facts and causes of action in Patel were very different from those in the current case, nevertheless “there can be little doubt that it was intended to provide guidance as to the proper approach to the common law illegality defence across civil law more generally.”

It is trite to conclude that outcome in Henderson seems somewhat obvious with hindsight. It wasn’t: the point was very arguable given that Patel was a split decision from only a few years ago and given that the doctrine of illegality has troubled the Supreme Court several times in the decade or so after Gray.

What Henderson actually does is to restate clearly the elements of the illegality defence in a unanimous decision by seven members of the Court, including its President and Deputy President. It does not at all follow from this that illegality will always be a complete bar to civil claims and, in a parallel judgment also delivered today five of the seven Justices involved in Henderson unanimously allowed a claim against solicitors for negligent failure to register title to a property despite the underlying transaction being an illegal mortgage fraud.

Lord Lloyd-Jones gave the judgment in that case (Stoffel v Grondona) and although he did not refer expressly to Henderson he also approved Lord Toulson’s analysis of the approach to illegality and concluded that: “the notion that persons should not be permitted to profit from their own wrongdoing is unsatisfactory as a rationale of the illegality defence … The true rationale of the illegality defence … is that recovery should not be permitted where to do so would result in an incoherent contradiction damaging to the integrity of the legal system.”


Alistair Kinley, Director of Policy & Government Affairs alistair.kinley@blmlaw.com

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