Mental health, manslaughter and the illegality defence – an analysis of Henderson v Dorset Healthcare University NHS Foundation Trust



The facts of Henderson v Dorset Healthcare University NHS Foundation Trust [2020] UKSC 43 are undeniably tragic: whilst in the grip of a severe psychotic episode Ms Henderson killed her mother.  She subsequently pleaded guilty to the offence of manslaughter by reason of diminished responsibility and was sentenced to a hospital order under s. 37 of the Mental Health Act 1983 (“the 1983 Act”) and an unlimited restriction order under s. 41 of the 1983 Act.   The tragedy is made only more acute by the fact that the defendant NHS Trust admitted that had the claimant received competent care she should have been returned to hospital on the basis of her manifest psychotic state and, had this been done, the killing would not have occurred.  Liability was denied by the Trust on the grounds that the damages claimed were the consequences of (i) the sentence imposed upon her by the criminal court; and/or (ii) her criminal act of manslaughter and were therefore irrecoverable by reason of the doctrine of illegality (also referred to as ex turpi causa non oritur actio).   Master Cook ordered that there be a trial of a preliminary issue to determine this question.  Ms Henderson’s claim failed on the basis of the illegality defence before Jay J, a decision that was upheld in the Court of Appeal and again in the Supreme Court decision handed down last week.

At first blush it might appear surprising that Ms Grondona, the mortgage fraudster in the case of Stoffel & Co v Grondona, is able to recover damages from her negligent conveyancing solicitors, but Ms Henderson cannot recover from the negligent defendant Trust.  One might also wonder how this decision fits with the recent Supreme Court decision of XX v Whittington Hospital NHS Trust [2020] 2 WLR 972, a case that was not referred to in Henderson.

The Courts have considered the operation of the illegality defence in similar circumstances to those of Ms Henderson at an authoritative level on two previous occasions: in the Court of Appeal in the case of Clunis v Camden & Islington Health Authority [1998] QB 987 and in the House of Lords in Gray v Thames Trains Ltd [2009] AC 1339.  On both occasions the claims failed.  Ms Henderson’s case raised the question of whether Gray could be distinguished and, if not, whether it should be departed from in particular in light of the Supreme Court decisions concerning illegality of Patel v Mirza [2016] AC 467.


In order to understand the above arguments and the court’s reasons for rejecting them it is necessary to consider Gray in some detail.  In that case the claimant was a passenger on a train involved in the Ladbroke Grove rail crash.  He suffered minor physical injuries but developed PTSD as a result.  While being treated for PTSD he stabbed to death a pedestrian who stepped in front of his car.  Like Ms Henderson he pleaded guilty to manslaughter on the grounds of diminished responsibility and was sentenced to be detained in hospital.  He brought a claim against the train company.  As Lord Hamblen summarised Mr Gray’s claim in Henderson:

“The claim for damages included damages which were the result of the sentence imposed on him, such as general damages for his detention and loss of earnings during it (“the narrow claim”). It also included damages which were the result of the killing, such as general damages for feelings of guilt and remorse consequent upon the killing and an indemnity against any claims which might be brought by dependants of the deceased (“the wide claim”).”

Lord Hoffmann summarised the defendant’s argument in Gray as follows (para 29):

“Their principal argument invokes a special rule of public policy. In its wider form, it is that you cannot recover compensation for loss which you have suffered in consequence of your own criminal act. In its narrower and more specific form, it is that you cannot recover for damage which flows from loss of liberty, a fine or other punishment lawfully imposed upon you in consequence of your own unlawful act. In such a case it is the law which, as a matter of penal policy, causes the damage and it would be inconsistent for the law to require you to be compensated for that damage.”

Lord Hoffmann held that the narrower rule was well established and that it was based on inconsistency (para 37):

“The inconsistency is between the criminal law, which authorizes the damage suffered by the plaintiff in the form of loss of liberty because of his own personal responsibility for the crimes he committed, and the claim that the civil law should require someone else to compensate him for that loss of liberty.”

The claimant’s argument that the sentence of detention was not a punishment but was a detention for treatment was rejected (para 41):

“In my view it must be assumed that the sentence (in this case, the restriction order) was what the criminal court regarded as appropriate to reflect the personal responsibility of the accused for the crime he had committed. As one commentator has said ‘Tort law has enough on its plate without having to play the criminal law’s conscience’: see EK Banakas [1985] CLJ 195, 197…”

As a result the narrow claim failed.

In respect of the wider rule, Lord Hoffmann explained that it was justified on the policy ground that:

 “… it is offensive to public notions of the fair distribution of resources that a claimant should be compensated (usually out of public funds) for the consequences of his own criminal conduct.”

As a matter of causation the immediate damage was caused by the claimant’s intentional criminal conduct.  Even though the conduct would not have occurred but for the defendant’s negligence, that merely provided the occasion for the claimant’s conduct.  As a result, in respect of the wider claim, Lord Hoffman concluded (at para 55):

“However the test is expressed, the wider rule seems to me to cover the remaining heads of damage in this case. Mr Gray’s liability to compensate the dependants of the dead pedestrian was an immediate ‘inextricable’ consequence of his having intentionally killed him. The same is true of his feelings of guilt and remorse.”

Lord Rodger, who wrote the other leading judgment, also rejected the narrow claim on grounds of inconsistency and the wide claim on the public policy ground that the claimant should not be entitled to recover for the consequences of criminal acts for which he had been found to be criminally responsible.

Lord Phillips, having agreed with the opinions of Lord Hoffmann and Lord Rodger went on to express the following obiter reservation about the application of the illegality doctrine:

“14. The comments of both Mustill LJ and Lord Bingham recognised that a mentally disordered offender whose mental condition did not satisfy the test of insanity or render him unfit to plead might none the less have no significant responsibility for his offence. Furthermore, while a conviction for an offence punishable with imprisonment is necessary to confer jurisdiction on a judge to impose a hospital order under section 37, the offence leading to that conviction may have no relevance to the decision to make the hospital order. Thus in R v Eaton [1976] Crim LR 390 a hospital order with a restriction order unlimited as to time was made in respect of a woman with a psychopathic disorder where her offence was minor criminal damage.

15. In such an extreme case, where the sentencing judge makes it clear that the defendant’s offending behaviour has played no part in the decision to impose the hospital order, it is strongly arguable that the hospital order should be treated as being a consequence of the defendant’s mental condition and not of the defendant’s criminal act. In that event the public policy defence of ex turpi causa would not apply. More difficult is the situation where it is the criminal act of the defendant that demonstrates the need to detain the defendant both for his own treatment and for the protection of the public, but the judge makes it clear that he does not consider that the defendant should bear significant personal responsibility for his crime. I would reserve judgment as to whether ex turpi causa applies in either of these situations, for we did not hear full argument in relation to them. In so doing I take the same stance as Lord Rodger.”

Lord Rodger also expressed a reservation in respect of the first of Lord Phillips’s first example (at para 83), but was silent as to his second reservation:

“The position might well be different if, for instance, the index offence of which a claimant was convicted were trivial, but his involvement in that offence revealed that he was suffering from a mental disorder, attributable to the defendants’ fault, which made it appropriate for the court to make a hospital order under section 37 of the 1983 Act. Then it might be argued that the defendants should be liable for any loss of earnings during the claimant’s detention under the section 37 order, just as they should be liable for any loss of earnings during his detention under a section 3 order necessitated by a condition brought about by their negligence. That point does not arise on the facts of this case, however, and it was not fully explored at the hearing. Like my noble and learned friend, Lord Phillips of Worth Matravers, I therefore reserve my opinion on it.”

The decision in Henderson

Issue 1: whether Gray could be distinguished

The appellant in Henderson sought first of all to distinguish Gray relying upon the second reservation expressed by Lord Phillips.  It was argued that Ms Henderson did not have significant personal responsibility for what had occurred and as a result her case was different to that of Gray.  For the purposes of the argument Lord Hamblen was prepared to assume that Mr Gray was regarded as bearing a significant degree of responsibility but went on to say (at para 83):

“The difficulty for the appellant, however, is that the degree of responsibility involved forms no part of the reasoning of the majority.  The crucial consideration for the majority was the fact that the claimant had been found to be criminally responsible, not the degree of personal responsibility which that reflected.”

On this basis Gray could not be distinguished.

Issue 2: Whether Gray should be departed from and Clunis overruled

On behalf of Ms Henderson it was argued that Gray should be departed from and Clunis overruled on a number of grounds, in particular:

(i) The reasoning in Gray could not stand with the approach to illegality adopted by the Supreme Court in Patel v Mirza [2017] AC 467, a decision that post-dated Gray in which the Supreme Court considered the operation of the illegality defence;

(ii) Gray should be held not to apply where the claimant had no significant personal responsibility for the criminal act and/or there was no penal element in the sentence imposed;

(iii) The application of the trio of considerations approach set out in Patel leads to a different outcome.

In respect of ground (i), it was argued that Gray is an example of the now discredited rule-based approach to illegality and is contrary to the flexible policy approach endorsed in Patel.  It was said that this approach did not allow the court to take into account the particular circumstances of the case, such as the degree of the claimant’s personal responsibility.  Nor does it allow for consideration of proportionality.

The Supreme Court rejected this argument, finding that the essential reasoning in Gray was consistent with the approach in Patel: that the fundamental policy consideration in Gray of the need for consistency so as to maintain the integrity of the legal system was the same as the underlying policy question in Patel.

Lord Hamblen said (from para 93):

Gray was correctly seen in Patel as being an example of a decision on illegality based on policy considerations rather than reliance. It was cited with apparent approval not only by Lord Toulson at paras 28-32, but also by Lord Kerr at para 129 and Lord Neuberger at paras 153 and 155.

“In addition, the fundamental policy consideration relied upon in Gray was the need for consistency so as to maintain the integrity of the legal system, the very matter that was held in Patel to be the underlying policy question.

“It is correct to observe that Gray involved no express consideration of proportionality. In Patel that did not, however, cause any doubt to be cast on the correctness of the decision and, for reasons explained below, the factual circumstances in Gray do not give rise to any issue of proportionality.

“The approach adopted by the House of Lords in Gray therefore provides no reason why it should be departed from. If anything, it points to the contrary conclusion.”

In respect of ground (ii) it was argued that the majority in Gray were wrong to decide that the narrower and wider rules applied regardless of the degree of personal responsibility.  It was said that this case raised on the facts the second reservation expressed by Lord Phillips because the trial judge accepted that the appellant did not bear a significant degree of personal responsibility for her crime, and that the Supreme Court should accept and apply that reservation.  The appellant’s fundamental point was that there is no inconsistency or incoherence between the civil and the criminal law in a case in which the claimant has no significant personal responsibility for a criminal act.  In fact denial of the tort claim would constitute a punishment in civil law that the criminal law had declined to punish; accordingly coherence was best served by tort law declining to do what the criminal law had refused to do.

These arguments were rejected. Lord Hamblen observed that the key consideration in Gray was that the claimant had been found criminally responsible for his acts and although the nature of the conviction meant that responsibility for the criminal act was diminished, it was not removed.  The same applied in the case of Ms Henderson.  Moreover the exercise of assessing levels of blame in any civil action raised questions of great complexity and risked inconsistency with the criminal law.

Ground 3 required the Supreme Court to consider whether approaching the case using the trio of considerations set out in Patel led to a different outcome.  Those considerations were:

(a) the underlying purpose of the prohibition which has been transgressed and whether that purpose will be enhanced by denial of the claim (“the first stage” or “stage (a)”);

(b) any other relevant public policy on which the denial of the claim may have an impact (“the second stage” or “stage (b)”); and

(c) whether denial of the claim would be a proportionate response to the illegality, bearing in mind that punishment is a matter for the criminal courts (“the third stage” or “stage (c)”).

With regard to stage (a) the Supreme Court identified relevant general policy considerations as being the consistency principle described above and also the public confidence consideration.  As Lord Hamblen said (from para 127):

“In the present case, the gravity of the wrongdoing heightens the significance of the public confidence considerations, as does the issue of proper allocation of resources. NHS funding is an issue of significant public interest and importance and, if recovery is permitted, funds will be taken from the NHS budget to compensate the appellant for the consequences of her criminal conviction for unlawful killing.

“This is also a case in which there is a very close connection between the claim and the illegality, thereby highlighting and emphasising the inconsistencies in the law which would be raised were the claim to succeed. The appellant’s crime was the immediate and, on any view, an effective cause of all heads of loss claimed. Indeed, applying Lord Hoffmann’s approach to causation in Gray, with which Lord Rodger and Lord Scott agreed, it was the sole effective cause of such loss.”

The underlying purpose of the prohibition transgressed was identified as to deter unlawful killing thereby providing protection to the public.  The Supreme Court rejected the contention that it was relevant that a person suffering from diminished responsibility would not be deterred, referring to this as a “granular level of diminished responsibility cases”.  Instead, more generally, the clear rule should be that “unlawful killing never pays and any such effect is important given the fundamental importance of the right to life.  To have such a rule also supports the public interest in public condemnation and due punishment.”

In respect of stage (b) the appellant identified four public policies said to weigh in favour of rejecting the defence: (i) encouraging the NHS to give competent care; (ii) compensating victims of torts where they are not significantly responsible for their conduct; (iii) ensuring public bodies compensate those they have injured and (iv) ensuring defendants in criminal trials receive sentences proportionate to their offending.  Whilst force was recognised in some of these, they did not “begin to outweigh those which support denial of the claim”, primarily being integrity of the legal system.

Stage (c) of Patel required considering four factors identified in that case: (i) the seriousness of the conduct; (ii) the centrality of the conduct to the transaction; (iii) whether the conduct was intentional; and (iv) whether there was a marked disparity in the parties’ respective wrongdoing.

The Supreme Court considered that the conduct was a very serious offence in respect of which the appellant knew what she was doing and that it was legally and morally wrong.  The offending was central to all heads of loss claimed and the effective cause of such loss.  There was intent to kill or to do grievous bodily hard and whilst there may have been no significant personal responsibility, there was nevertheless murderous intent.  In terms of whether there was marked disparity in the parties’ respective wrongdoing, the appellant was convicted of culpable homicide set against negligent treatment although not a case where the respondent’s staff did nothing in response to her mental health relapse.  In those circumstances denial of the claim was not disproportionate.

Issue 3: whether all heads of loss are irrecoverable

It appears to have been conceded that damages for loss of liberty and loss of amenity during detention were barred by the narrower rule in Gray and the other heads were barred by the wider rule.  There was said to be “some retreat from this position” in respect of the head of loss relating to the Forfeiture Act 1982.  It was held that the court had made an order under the Forfeiture Act 1982 barring the appellant from receiving a share in her mother’s estate and it would be inappropriate to subvert the operation of that regime by permitting her to recover under that head of claim


In a nutshell the Supreme Court has affirmed that the decision in Gray is consistent with the later judgment of Patel.  Although on the face of the two cases the different results for Ms Grondona and Ms Henderson might appear inconsistent, an analysis of the two decisions shows the clear differences between them and also demonstrates the assistance the reasoning set out in Patel provides in practice when analysing different cases.

Bearing in mind that Henderson is a clinical negligence case, some practitioners in the field might be wondering how the decision fits with the recent Supreme Court decision in XX v Whittington (in which Edward Faulks QC of 1 Chancery Lane acted for the Trust), which also touched upon questions of illegality and does not appear to have been cited in Henderson. 

The emphasis by the Supreme Court in Henderson on the importance of coherence in the law also chimes with views of the minority in XX.  In that case, the court held by a majority that a victim of medical negligence could recover the costs of a commercial surrogacy to be incurred in California, even though such a surrogacy arrangement would not have been lawful in the UK.  The minority would have rejected the claim on the basis that it would be inconsistent and incoherent for the UK’s civil courts to award damages in respect of conduct which would be criminal if it was committed here.  Nonetheless the entire court agreed that the case was not one in which the doctrine of illegality had any application, because UK law did not criminalise entering into a commercial surrogacy abroad and the proposed surrogacy was lawful in California, a distinction which might be thought to be rather subtle.

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