Is retained responsibility a matter for expert psychiatric evidence?

On 2 May 2025, 84-year-old Roger Worby pleaded guilty to the manslaughter on the grounds of diminished responsibility of his wife. ¹ It was his case that he was acting on the basis of a suicide pact made with his wife.

The court had supportive evidence from Dr Pratish Thakkar, consultant forensic psychiatrist, instructed by the defence. The Crown then instructed Dr Iain Kooyman, consultant forensic psychiatrist, who prepared a report which was also supportive of the defence. He subsequently prepared an addendum report, according to the sentencing remarks of the judge, HHJ Simon, the Honorary Recorder of Luton, ‘offering what assistance he felt able to in relation to the level of retained responsibility’. According to these sentencing remarks, the expert's clear opinion was that Mr Worby's actions were heavily impacted by his impaired judgement as a result of his mental disorder, and his level of retained responsibility was ‘in the Lower category’. As a result of a difference of opinion as to diagnosis, in that Dr Thakkar diagnosed an acute and transient psychotic disorder and Dr Kooyman diagnosed a state of generalised anxiety with over-valued paranoid ideas arising from catastrophic thinking, on the invitation of the Crown and the defence, the court instructed a third consultant forensic psychiatrist, Professor Seena Fazel, specifically to assist the court with his level of retained responsibility. The thrust of his evidence was that the level of retained responsibility was low although he added that there was some uncertainty given the lack of corroborative information about the deceased's views.

Ms C Carberry KC submitted for the Crown that the planning involved in preparing a hammer and knives and Mr Worby's actions of tidying around after the event and calling 999 demonstrated purposeful behaviour. So, the Crown suggested that the level of retained responsibility fell between the medium and the lower. For Mr Worby, Mr L Selby KC submitted that as he genuinely believed there was a suicide pact, and taking into account all of the evidence, the court should settle on the lower level of retained responsibility.

HHJ Simon did not view the bringing of the hammer into the bedroom from the neighbouring room, the placing of knives in the workshop, the tidying up afterwards, or the fact that the table was laid out for breakfast as in any way inconsistent with acting entirely in accordance with the reality created in his mind as a result of his mental disorder. He said that the table laid for breakfast was nothing more than evidence of what one neighbour called ‘an old school couple’, who, especially post-Covid, had a relatively mundane and routine way of life, anchored to the home setting. The judge went on to place Mr Worby's retained responsibility in the lower category.

This case has prompted discussion as to whether retained responsibility is properly an issue for psychiatric expertise.

The sentencing guidelines

The Sentencing Council guidelines ‘Manslaughter by reason of diminished responsibility’ ² identify the first step in the sentencing process as ‘Assessing the degree of responsibility retained: high, medium or lower’. The Guidance is set out in Box 1.

Box 1.

Sentencing Council guidance on assessing the degree of retained responsibility

A conviction for manslaughter by reason of diminished responsibility necessarily means that the offender's ability to understand the nature of the conduct, form a rational judgment and/or exercise self-control was substantially impaired.

The court should determine what level of responsibility the offender retained:

High;

Medium; or

Lower

The court should consider the extent to which the offender's responsibility was diminished by the mental disorder at the time of the offence with reference to the medical evidence and all the relevant information available to the court.

The degree to which the offender's actions or omissions contributed to the seriousness of the mental disorder at the time of the offence may be a relevant consideration. For example:

Where an offender exacerbates the mental disorder by voluntarily abusing drugs or alcohol or by voluntarily failing to seek or follow medical advice, this may increase responsibility. In considering the extent to which the offender's behaviour was voluntary, the extent to which a mental disorder has an impact on the offender's ability to exercise self-control or to engage with medical services will be relevant.

The degree to which the mental disorder was undiagnosed and/or untreated may be a relevant consideration. For example:

Where an offender has sought help but not received appropriate treatment this may reduce responsibility.

Having determined the category at step one, the court then uses the corresponding starting point to reach a sentence within a defined category range. So, if the level of retained responsibility is ‘high’ the starting point is 24 years’ custody with a category range of 15–40 years’ custody whereas if it is ‘lower’ the starting point is 7 year's custody with a category range of 3–12 years’ custody. Thus, the level of retained responsibility is proportional to the degree of punishment as measured by years in prison custody.

The guidance does refer specifically to the relevance of ‘medical evidence’ in that the court has to ‘consider the extent to which the offender's responsibility was diminished by the mental disorder at the time of the offence with reference to the medical evidence’, but this is along with ‘all the relevant information available to the court’. Furthermore, the examples given of relevant actions or omissions that contributed to the seriousness of the mental disorder and of the degree to which the mental disorder was undiagnosed and/or untreated are ones that illustrate the likely reliance of the court on medical evidence.

Case law

It was a ground of appeal in R v Rodi [2020] EWCA (Crim) 330 that the applicant's overall custodial sentence was manifestly excessive in part because the sentencing judge took a starting point that was significantly above that mandated at the highest level of retained responsibility. This appeal was unsuccessful. The court said in its judgment that ‘assessment is a matter to be weighed by the judge upon his or her view of the circumstances of the killing and the medical evidence which may bear on the question’.

In R v Westwood [2020] EWCA Crim 598 (‘Westwood’) Dr Shivaprasad gave oral testimony at the sentencing hearing. She was asked about the degree of retained responsibility. She identified five factors that she thought should be considered:

The appellant's ‘disposition or his personality’.

His alcohol and drug use

‘[T]he stresses that might come from living with a significant other’.

‘[P]sychological stress’.

The appellant's ‘mental illness’.

However, given the opportunity to offer her own view on the appellant's retained responsibility, and in particular whether she was able to put it at ‘a level of low, medium or high’, she expressed no opinion. The judge went on to fix the appellant's level of retained responsibility as ‘medium to high’. In finding the judge to have been in error, and taking the view that the only realistic conclusion was that the appellant's retained responsibility was low, the court thought that this was clearly indicated by the medical evidence before the judge and amply supported by the subsequent psychiatric reports.

Psychiatric evidence as to the significance of the appellant's smoking of strong ‘skunk’ cannabis and drinking of spirits in the 48 h before the offence was an issue in R v Byrne [2022] EWCA Crim 1630. Although the appellant knew his condition was exacerbated by the use of alcohol and illicit drugs, this did not accord with the psychiatric evidence that it would not have had any impact upon his paranoid schizophrenia, nor his actions on the night in question, and there was also evidence that the appellant used alcohol and drugs in order to self-medicate. In this case the sentencing judge decided that the level of retained responsibility was low and the Court of Appeal, referring to the sentencing judge's assessment said: ‘In determining the extent to which the offender's responsibility was diminished by the mental disorder at the time of the offence the judge must have regard to the medical evidence and all the relevant information available to the court.’

The Court of Appeal in R v Oliver [2023] EWCA Crim 336 (‘Oliver’) said: ‘The assessment of the level of responsibility retained in a case of manslaughter by virtue of diminished responsibility is not a mathematical exercise. It does, however, require a careful analysis of all the relevant factors and a precise calibration of the case within the guideline.’

The sentencing judge in R v Bennis [2025] EWCA Crim 538 assessed the level of the applicant's retained responsibility as medium and for the following reasons:

Her complex post-traumatic stress disorder was undiagnosed, such that she was not in a position to understand how her condition might cause her to act so violently.

The consumption of a considerable amount of alcohol, which exacerbated her condition.

She was aware that alcohol heightened her fight or flight responses.

She was obviously angry with the deceased in the lead up to the killing.

She made an obviously poor choice to go alone to the deceased's flat.

She had some self-awareness of acting violently, as she had done when assaulting a police officer by punching and biting the officer a year previously.

In this case, the Court of Appeal was not persuaded that there was any arguable error in the judge's evaluative assessment of retained responsibility. It referred to the judge identifying a number of factors relevant to his assessment that the level of retained responsibility was medium and which, in its judgment, afforded a wholly reasonable basis for that conclusion.

Some preliminary conclusions

Sentencing judges are expected to have regard to the medical evidence when assessing the degree of retained responsibility.

Sentencing judges are also expected to have regard to all the relevant information available to the court.

Other relevant considerations, specifically the degree to which the offender's actions or omissions contributed to the seriousness of the mental disorder at the time of the offence and the degree to which the mental disorder was undiagnosed and/or untreated, can be informed by medical evidence.

Assessment of the level of retained responsibility is a matter to be weighed by the judge.

To refuse, to offer a qualified opinion or to do as instructed?

Dr Shivaprasad in Westwood identified five matters that she considered relevant to the court's assessment of retained responsibility. She declined to give an ‘opinion’ as to retained responsibility. This is understandable. She might reasonably have considered that she did not have all the relevant information available to the court. It was a matter for the court's assessment.

Dr Kooyman, instructed by the Crown in Mr Worby's case, offered ‘what assistance he felt able to’ (author's italics for emphasis). That he offered assistance suggests that he had not been instructed to address the issue although as this was an appendix report it is possible that the issue was raised in a subsequent instruction. Be that as it may, it was no more than an offer and it was up to the court whether to accept or reject that offer of assistance. It is for the court to decide whether it needs the assistance of an expert. It is well-established law that the expert gives evidence but the court decides the issue. Furthermore, it is implicit that the expert made clear that there were limits to the assistance that he could offer. Like the expert in Westwood, he may have had in mind, or perhaps even made clear, that he did not have all the relevant information available to the court.

Professor Fazel, the court-appointed psychiatrist in Mr Worby's case, was ‘instructed specifically to assist the Court’ (author's italics for emphasis) with the level of retained responsibility. Given that the Crown and defence experts disagreed as to diagnosis and one of them had offered a qualified opinion as to retained responsibility, it is not surprising that Professor Fazel was specifically instructed to assist as to the level of retained responsibility. Here, the court was actively looking for assistance. The court was not asking the expert to decide the issue. Dr Kooyman had expressed the opinion that Mr Worby's actions were heavily impacted by his impaired judgement as a result of his mental disorder, that his mental disorder was undiagnosed and therefore untreated and there was no evidence of the consumption of alcohol or illicit drugs. In the circumstances it understandable that the court should also ask its appointed expert about retained responsibility. Again, the expert's view was qualified. He obviously recognised that this was not a purely medical matter but one that would be informed by other information as he referred to how the absence of corroborative information about the deceased's views meant that his view on retained responsibility was thereby somewhat uncertain.

One feature of Mr Worby's case which illustrates the potential value of medical evidence when assessing the level of retained responsibility is the Crown's submission that his ‘purposeful behaviour’ made the level of retained responsibility not ‘lower’ but between ‘lower’ and ‘medium’. As it happens, the judge did not accept this submission and pointed out that this behaviour was entirely in accordance with the reality created in his mind as a result of the mental disorder. This is a point which it is often necessary for experts to make. Medical evidence can assist as to whether or not behaviour is explicable by the abnormality of mental functioning which the court has accepted or found, or will accept or find, to have substantially impaired the offender's ability to do one or more of the things mentioned in the Homicide Act 1957, s 2(1A).

Another feature of the case illustrates the importance of the court having regard to all the relevant information available to it. The Crown's submission that the level of retained responsibility was higher than ‘Lower’ rested in part on the fact that the table was laid out for breakfast but the evidence of a neighbour about Mr Worby and his wife being ‘an old school couple’ with a relatively mundane and routine way of life, anchored to the home setting, countered this submission.

How does this differ, if at all, from psychiatric evidence and culpability?

Since 2020 Hallett's paper ‘To what extent should expert psychiatric witnesses comment on criminal culpability?’ ³ has become influential for its critical examination of the boundaries of expert psychiatric testimony regarding culpability. Box 2 sets out the abstract of his paper. Clearly there are parallels.

Box 2.

Abstract from ‘To what extent should expert psychiatric witnesses comment on criminal culpability?’

Following the court of appeal case of R v Edwards in England and Wales, there has been increasing pressure for expert psychiatric witnesses to comment explicitly on how a defendant's mental disorder affects their culpability. Culpability is the degree to which a person can be held morally or legally responsible for their conduct, but defining culpability has proved difficult. Mental disorder does not translate easily into degrees of legal culpability. Although psychiatric evidence will often be central to such cases, the determination of culpability is a matter for the court, and experts should not comment on it explicitly. Nevertheless, certain areas of psychiatry may have a bearing on culpability, and ways in which experts may comment on these are suggested. Given the pressure on judges to determine culpability, experts need to be honest about the limits of medical science to answer legal questions and the professional necessity to remain within their area of expertise.

Responsibility is widely considered a foundational moral concept within philosophy and ethics and when someone is held morally responsible, it implies that they acted (or failed to act) in a way that warrants moral praise, blame, reward, or punishment. Just as the court assesses culpability to decide the punishment element of a sentence, the court assesses retained responsibility to determine the starting point for a custodial sentence. But, as with culpability, defining ‘retained responsibility’ is difficult. It would be easier if there were a legal definition of ‘diminished responsibility’, but close examination of the Homicide Act reveals that the term is not found in section 2 itself and only in its cross-heading, ‘Persons suffering from diminished responsibility’. It is reasonable to infer that what is retained is the responsibility that does not originate in a recognised medical condition. That being so, it might be argued that it is not a matter for medical evidence.

It may be said, as for culpability, that retained responsibility does not translate easily into legally defined levels of responsibility. As the court said in Oliver, it is not a mathematical exercise. Although the term ‘retained’ clearly refers to what has been left, that which, as it were, has been extracted, is not quantified in any meaningful way. It has only been quantified to the extent that on a balance of probabilities the requirements of section 2 have been satisfied but whether the likelihood was 51% v 49% or 91% v 9% is not known.

In the case of culpability, Hallett says that although psychiatric evidence will often be central to such cases, the determination of culpability is a matter for the court, and experts should not comment on it explicitly. Just as ‘questions of culpability are for the court’ (R v Weldemaryam [2020] EWCA Crim 1616), the same can be said about retained responsibility. Should experts comment explicitly on retained responsibility? The answer is probably ‘no’ but Mr Worby's case can be seen as an exception to the rule. It was exceptional in that the court itself specifically instructed its expert to assist on this matter. But it only asked for assistance; it did not ask the expert to decide the matter. In practice, because most if not all of the required medical evidence is already available to the court in the form of reports prepared for trial, supplemented in some cases by oral testimony, it is probably uncommon for further psychiatric evidence to be required for sentencing but these are likely to be cases where the courts may be specific in asking for assistance on retained responsibility.

Again, to paraphrase Hallett, given the responsibility of judges to assess retained responsibility, experts need to be honest about the limits of medical science to answer legal questions and the professional necessity to remain within their area of expertise.

Conclusions

Retained responsibility is a matter for expert psychiatric evidence. Ultimately, the assessment is for the court, a matter for judicial inference and analysis, but psychiatric evidence may assist. It may be advisable to point out that retained responsibility, like diminished responsibility, is not a psychiatric concept but a moral or legal concept and that this may limit the usefulness of the psychiatric assistance offered or provided. As in any case, the expert should make clear their evidential basis, so it may be advisable to acknowledge that there may be other relevant information available to the court outside the knowledge of the expert. As in any case, if an expert does not have the knowledge or experience to address a particular issue, they should not hesitate to refuse.