Smithers was a black player on a hockey team, and members of the opposing team (particularly Cobby) racially insulted him during a game. About 45 minutes after the game he ran up to Cobby and punched him twice in the head, and Cobby doubled over. Then he kicked him in the stomach and Cobby fell to the ground and within five minutes appeared to stop breathing. Cobby was dead on arrival at the hospital and the cause of death was determined to be "spontaneous aspiration from vomit" during an autopsy – choking on his own vomit. Cobby's epiglottis malfunctioned, and this led to his death. Smithers was convicted of manslaughter at trial and the conviction was upheld on appeal.
- Was the kick a sufficient cause of the death to attract criminal liability?
Appeal dismissed, conviction upheld.
Dickson, writing for the court, said that the kick had to be an "operating cause outside of the de minimis range" in order for it to be deemed the cause of death, that is, the Crown had to prove that the kick caused the vomiting, and that the vomiting caused the death. He accepts the Crown's argument that this was outside the de minimis range, as the thin skull rule applies in criminal law and therefore the kick led to the victim's reaction that resulted in death. This is a lower standard than the Smith test, which is what the defence wanted to be used. The Smithers test needs a lower threshold of causation to be proven in order to get the conviction.
- An action only has to be an operating cause outside of the de minimis range in order to be deemed the cause of a prohibited result in criminal law; a lower threshold of causation than was required in the Smith test.
- The "thin skull" rule applies in criminal law as in tort law.