Where an accused contends that perceptions of events were substantially impaired or that ability to form a rational judgment as to right and wrong was substantially impaired, the trial judge must convey to the jury the need to consider those aspects of mental responsibility, though the judge is not required to relate the law to the evidence in detail if the issues have been identified and the psychiatric evidence has pointed up the areas of agreement and disagreement. A head sentence for murder must make allowance for an abnormality of mind even where the jury has rejected the defence of diminished responsibility, and must also reflect the harsher conditions of protective custody.
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