## Facts

- Daniel Golds, the appellant, admitted to killing his partner and raised the partial defence of diminished responsibility, citing psychosis associated with schizophrenia.
- At trial, the jury was instructed that "substantial impairment" meant more than slight or minor impairment.
- The Court of Appeal upheld this direction.
- Golds appealed to the Supreme Court, arguing the jury guidance was incorrect.

## Issues

1. Whether the legal standard for "substantial impairment" in section 2(1) of the Homicide Act 1957 (as amended by section 52 of the Coroners and Justice Act 2009) required further definition beyond its ordinary meaning.
2. Whether judicial explanations such as "more than minimal" or "more than trivial" should be given to help juries interpret "substantial impairment."
3. Whether the responsibility for assessing the evidence and determining if the impairment was "substantial" lies with the jury or with medical experts.

## Decision

- The Supreme Court ruled that "substantial impairment" should be given its normal, everyday meaning and does not require further judicial explanation.
- The Court found that additional definitions or scales (e.g., "more than minimal" or "clear and noticeable") could confuse juries and undermine the statute's intent.
- The final determination of whether impairment was substantial should be left to the jury, who must consider all the evidence, including but not limited to medical expert opinions.

## Legal Principles

- The partial defence of diminished responsibility requires the defendant to demonstrate an abnormality of mental functioning resulting from a recognised medical condition that substantially impairs their ability to understand their conduct, form rational judgement, or exercise self-control.
- The term "substantial impairment" is to be understood in its plain meaning, without the need for judicial gloss or scale.
- It is for the jury, not medical experts, to decide whether the defendant's impairment meets the threshold of being "substantial."
- Medical evidence is essential for assisting the jury but is not determinative.

## Conclusion

The Supreme Court clarified that "substantial impairment" under diminished responsibility in murder cases should be understood according to its ordinary meaning, eschewing additional judicial explanations, and leaving the assessment to the jury based on all available evidence. This ruling ensures consistent legal application and emphasizes the importance of careful jury consideration in cases involving mental health.

R v Golds [2016] UKSC 61