Osborne, R v

A later diagnosis of ADHD does not, without more, establish diminished responsibility. The evidence must show that the abnormality of mind substantially impaired mental responsibility at the time of the killing. The court must assess expert psychiatric evidence against the whole factual context, including deliberate and calculated conduct.

Under section 23 of the Criminal Appeal Act 1968, fresh evidence may be capable of belief and its earlier absence sufficiently explained, yet still be excluded where its admission is neither necessary nor expedient in the interests of justice. The decisive question remains whether the evidence could have affected the jury’s verdict and rendered the conviction unsafe.

The appellant, aged 14 at the time, was convicted at Snaresbrook Crown Court of murder after chasing the deceased with two companions, obtaining a piece of wood, and delivering a fatal blow to the head. His appeal against conviction was dismissed in November 2005.

The Criminal Cases Review Commission later referred the case on fresh psychiatric and psychological evidence said to show ADHD. The appellant contended that the condition supported both diminished responsibility and the absence of the intent required for murder. The court considered whether the evidence should be admitted and whether it affected the safety of the conviction.

1. Appeal dismissed. The conviction remained safe. The court declined to admit the fresh expert evidence because its admission was neither necessary nor expedient in the interests of justice, and it would not have affected the jury’s decision.

2. The court accepted, on the balance of probabilities, that the appellant had some degree of ADHD at the time of the killing. It also accepted that the proposed expert evidence was capable of belief, would have been admissible at trial, and that its absence at trial was sufficiently explained for the purposes of section 23 of the Criminal Appeal Act 1968.

3. However, ADHD is not by itself sufficient to establish the degree of diminished responsibility required by law. The evidence did not establish that the condition substantially impaired the appellant’s mental responsibility. The evidence of severity was not made out, and the circumstances of the killing showed calculation and deliberation rather than an uncontrolled impulsive response.

4. The appellant had time to reflect after the initial confrontation. He and his companions deliberately obtained weapons, pursued the deceased after he was out of sight, and attacked him when he was defenceless. No properly directed jury could have found diminished responsibility established on the basis of the ADHD evidence.

5. The fresh material would also have disclosed a history of violent behaviour. It would therefore have weakened, rather than strengthened, a defence based on absence of intent. The jury’s verdict would have been unaffected.

• Court of Appeal (Criminal Division): On a reference by the Criminal Cases Review Commission, the court dismissed the appeal and held the conviction safe: [2010] EWCA Crim 547.

• Earlier appeal: The appellant’s appeal against conviction was dismissed on 2 November 2005. The court and citation are not stated in the judgment.

• Crown Court at Snaresbrook: The appellant was convicted of murder on 15 April 2005 and sentenced to detention for life with a minimum term of nine years, subject to appropriate credit for time served.