Donoghue v Stevenson 
The claimant, Mrs Donoghue, visited a café with her friend who bought her a ginger beer from the café. The ginger beer came in an opaque bottle, making it impossible to see its contents from the bottle. The claimant drank some of the ginger beer, and when she poured the remaining beer into a glass, she saw the remains of a decomposed snail emerging from the bottle. She claimed to have suffered shock and severe gastroenteritis. As there was no contractual relation between Mrs Donoghue and the manufacturers of the ginger beer, Mr Donoghue brought an action against the manufacturer of the ginger beer, Stephenson, for damages.
Whether or not the defendant, as the manufacturer of the ginger beer, owed a duty of care to Mrs Donoghue in the absence of contractual obligation.
In a 3-2 majority, that the defendant owed a duty of care to Mrs Donoghue even in the absence of contractual obligation.
Lord Atkin established what has become known as the neighbour principle which essentially states that a duty of care is owed to persons who are close enough to be affected by our actions. He said:
The rule that you are to love your neighbour becomes in law, you must not injure your neighbour; and the lawyer's question, Who is my neighbour? receives a restricted reply. You must take reasonable care to avoid acts or omissions which you can reasonably foresee would be likely to injure your neighbour. Who, then, in law, is my neighbour? The answer seems to be – persons who are so closely and directly affected by my act that I ought reasonably to have them in contemplation as being so affected when I am directing my mind to the acts or omissions which are called in question
This rule has substantially influenced the tort of negligence and provided a way to determine if a duty of care exists in novel situations.