Cowan (AKA Shaddo N-Unyah Hunter) v The Queen

The High Court of Australia considered an appeal by Cowan (also known as Shaddo N-Unyah Hunter) against his conviction for murder. The central dispute concerned the admissibility of certain evidence during his trial, specifically evidence relating to his mental state at the time of the offence.

The primary legal issue before the High Court was whether the trial judge had erred in admitting evidence of the appellant's prior convictions and prior bad character, which the appellant argued was unfairly prejudicial and irrelevant to the question of his guilt. A further issue concerned the proper application of the principles governing the admissibility of evidence of an accused's mental state, particularly in the context of a defence of provocation.

The High Court held that the admission of the evidence of prior convictions and bad character was an error. Their Honours reasoned that this evidence had not been properly admitted under any exception to the general rule against admitting such evidence, and its prejudicial effect on the jury's assessment of the appellant's guilt far outweighed any probative value. The Court also found that the trial judge's directions to the jury regarding the appellant's mental state were inadequate, failing to properly explain how evidence of his mental state could be considered in relation to the defence of provocation.

Consequently, the High Court allowed the appeal, quashed the conviction, and ordered a new trial.