Clarifying Retained Responsibility and Extended Licence Periods in Diminished-Responsibility Manslaughter

1. Introduction

This judgment arises from the renewed application by the appellant, Ms. Bennis, for leave to appeal her sentence for the manslaughter (by reason of diminished responsibility) of her mother in August 2022. At first instance, the Central Criminal Court found that the appellant—then aged 21—was suffering from undiagnosed complex post-traumatic stress disorder (CPTSD) and alcohol use disorder, and imposed an extended determinate sentence under section 279 of the Sentencing Act 2020: nine years’ custody and a five-year extended licence period for public protection. The sole issue before the Court of Appeal (Criminal Division) was whether that sentence—and in particular the judge’s assessment of the appellant’s level of “retained responsibility” and the length of her extended licence—was demonstrably wrong or inadequately reflected her lifelong history of abuse.

Key parties:

• The appellant: Aziza Bennis, convicted of manslaughter by reason of diminished responsibility.
• The Crown: opposing further reduction in sentence.
• The Court below: His Honour Judge Nigel Lickley KC.
• The Court of Appeal panel: Lord Justice Evans, Lord Justice Dove, and Lady Justice Whipple.

2. Summary of the Judgment

The Court of Appeal refused the appellant’s renewed application for leave to appeal. It held that:

1. There was no error of principle or demonstrable unfairness in the sentencing judge’s application of the applicable legislative framework (Homicide Act 1957, section 2(1)) and the Sentencing Council’s Manslaughter: Diminished Responsibility guideline.
2. The judge’s assessment that the appellant’s retained responsibility was “medium” (rather than “low”) was fully supported by evidence: undiagnosed CPTSD, substantial alcohol consumption, prior violence in 2021, ferocity of the attack, and limited self-awareness of her condition.
3. The starting point of 15 years (range 10–25), reduced to 13½ years before plea credit and 9 years’ custody in total, was towards the lower end of the guideline range and plainly reasonable.
4. The five-year extended licence period was a legitimate exercise of the judge’s discretion to protect the public given the ongoing risk posed by the appellant’s unresolved mental health issues.

No arguable merit was found in the grounds seeking further reduction of the custodial term or the licence period.

3. Analysis

3.1 Precedents and Legislative Framework

Though the judgment did not cite prior appellate decisions by name, it built upon well-established authorities and statutory provisions:

• Homicide Act 1957, section 2(1): establishes diminished responsibility as a partial defence to murder, requiring “abnormality of mental functioning” that substantially impaired the defendant’s ability to (a) understand the nature of their conduct, (b) form a rational judgment, or (c) exercise self-control.
• Sentencing Act 2020, section 279: provides for extended determinate sentences where the offender is assessed as “dangerous,” combining a custodial term with an extended licence period.
• Sentencing Council Guidelines:
  • Manslaughter: Diminished Responsibility: sets out starting points and ranges based on “level of responsibility retained” (high, medium, low).
  • Manslaughter by Reason of Loss of Control: referenced by the defence for “calibration,” but held inapplicable when the appellant pleaded solely to diminished responsibility.

The Court reiterated that a judge must apply the guideline corresponding to the plea and cannot “calibrate” by reference to an alternative partial defence guideline once a plea basis is fixed.

3.2 Legal Reasoning

The Court’s reasoning unfolded in three stages:

1. Validation of the Judge’s Principles: The sentencing judge conducted a comprehensive analysis of the facts, pre-sentence report, psychiatric evidence, aggravating and mitigating factors, and legislative mandates. No error of principle or misapplication of guidelines was identified.
2. Assessment of Retained Responsibility: The central dispute was the rating of “medium” retained responsibility. The judge weighed:
   • The appellant’s substantial impairment of self-control due to CPTSD.
   • The amplifying effect of heavy alcohol consumption.
   • The undiagnosed nature of her condition, which prevented self-awareness.
   • Her prior violent behaviour (assault on a police officer in 2021).
   • The ferocity and sustained nature of the knife attack.
   The Court held that these factors legitimately distinguished her from a “low responsibility” category.
3. Proper Exercise of Discretion on Licence Period: Under section 279, the judge assessed the ongoing risk. Though the appellant had prospects of rehabilitation, unpredictable compliance with treatment and the seriousness of the offence justified a five-year extended licence.

3.3 Impact on Future Cases

This decision reinforces key principles for sentencing in diminished-responsibility cases:

• Deference to the trial judge’s evaluative judgment on retained responsibility where supported by evidence.
• Strict adherence to the guideline corresponding to the plea, precluding “cross-calibration” with alternate partial-defence guidelines.
• Affirmation that extended licence periods under section 279 are reviewed only for legal error or irrationality, not merely disagreement with the length.

Future appellants disputing a medium categorisation will face a high threshold: they must show an arguable error in principle or evaluation, not just contest the weighting of factors.

4. Complex Concepts Simplified

1. Diminished Responsibility: A defence that reduces murder to manslaughter if the defendant’s mental functioning was abnormal and substantially impaired specific capacities.
2. Retained Responsibility: The measure of how much culpability remains after discounting the impairment: “high,” “medium,” or “low.”
3. Extended Determinate Sentence: Combines a fixed custodial term with an additional licence period, on which the offender can be recalled if they pose danger after release.
4. Calibration: Informal reference to comparing one guideline with another; rejected once the plea basis dictates the applicable guideline.

5. Conclusion

The Court of Appeal’s decision in Bennis, R. v. ([2025] EWCA Crim 538) confirms that, in manslaughter by reason of diminished responsibility, a judge’s nuanced evaluation of retained responsibility—even where mental disorders are undiagnosed—will not be disturbed absent a clear misapplication of principle. Likewise, the discretion to set an extended licence period for public protection is entitled to deference so long as it is rationally linked to the offender’s assessed risk. This ruling thus provides clarity on the interplay between psychiatric impairment, alcohol misuse, sentencing guidelines, and the statutory framework for extended determinate sentences.