In cases of manslaughter by criminal negligence involving a breach of duty, the ordinary principles of the law of negligence applied to ascertain whether D had been in breach of a duty of care towards V, whether it caused the death of V, and if so, whether it should be characterized as gross negligence and therefore a crime. Having regard to the risk of death involved, was D’s conduct so bad in all the circumstances as to amount to a criminal act or omission?

D had given V drugs. V fell ill but did not call an ambulance.

D could not be convicted of gross negligence manslaughter because it had been shown that if he had called an ambulance V’s life would definitely have been saved.

D had taken a woman to his van for sexual purposes and she mocked him for failing to satisfy her. During a fist fight between them, D knocked V semi-conscious. Thinking she was dead, D panicked and threw V into a river, where she died from drowning.

The Court of Appeal dismissed his appeal. The test for dangerous is that the unlawful act must be such that all sober and reasonable people would inevitably recognize it as an act which must subject the other person to at least the risk of some (physical) harm resulting therefrom, albeit not serious harm.

Two 15-year-old boys pushed a paving stone over a bridge and into the path of an oncoming train. The stone went through the glass window of the cab and killed the guard.

It is manslaughter if it is proved that D intentionally did an act which was unlawful and dangerous and that act inadvertently caused death. It was unnecessary to prove that D knew that the act was unlawful or dangerous or whether D recognized its danger.

The defendants—a partially deaf and almost blind man of below average intelligence and no appreciable sense of smell, and his partner, who was ineffectual and inadequate—lived together in his house with his mentally subnormal son.
The man’s anorexic sister, V, came to live at the house as a lodger. She refused to eat and rejected the defendants’ (limited) assistance. V died from toxaemia spreading from infected bed sores, prolonged immobilization, and lack of food.

On the facts, the jury had been entitled to find the defendants had assumed a duty to care for V and were obliged to summon help or care for V themselves when she became helplessly infirm.
The breach of duty which had to be established was a reckless disregard of danger to her health and welfare by indifference to an obvious risk of injury to health or by actually foreseeing the risk and determining nevertheless to run it.