R v Leonboyer

The defendant, Leonboyer, was convicted of murder and appealed against the conviction and sentence. The appeal raised questions about the adequacy of the defence of non-insane automatism, the role of expert medical evidence, the application of the objective test for provocation, and the potential influence of personal characteristics of the accused on the jury's assessment of provocation. Additionally, the appeal questioned whether the trial judge had unduly influenced the jury and whether the sentence was based on incorrect factual foundations.

The court examined whether the trial judge had correctly directed the jury on the defence of non-insane automatism, considering the possibility that expert medical evidence might mislead the jury. It assessed whether the trial judge had appropriately applied the objective test for provocation, taking into account the gravity of the provocation and whether words alone could constitute sufficient provocation. The court also considered whether the judge had unduly influenced the jury and if the sentence was grounded on incorrect facts.

In its reasoning, the court concluded that the trial judge had correctly directed the jury on the defence of non-insane automatism, and there was no undue influence on the jury by the judge. The court found that the evidence was sufficient to support the jury's conclusion that the defendant acted consciously and voluntarily, rejecting the defence of involuntary action. Regarding provocation, the court held that the trial judge had correctly applied the objective test, and the evidence supported the jury's finding that the provocation was not sufficient to reduce the charge to manslaughter. Finally, the court found that the sentence was based on an incorrect factual premise, as it relied on an assumption that was not supported by the evidence.

Consequently, the court allowed the appeal against the conviction but not the sentence. The conviction was quashed and a retrial ordered. The sentence was affirmed as there was no basis to alter it based on the court's findings.