Donoghue v. Stevenson
Mrs. May Donoghue ordered an ice-cream drink, which included ginger beer, from a café. When she had already consumed some of the drink, her friend tipped out some more ginger beer into the drink, and it became apparent that the decomposing remains of a snail had been present in the bottle of ginger beer. Mrs. Donoghue later suffered from shock and gastroenteritis, and sued the manufacturer of the ginger beer for the harm she suffered.
Lord Atkin famously derived his 'neighbour principle', under which the manufacturer of the ginger beer owed a duty of care to the consumer, from Christian principles (specifically, Luke 10). He ruled that the manufacturer of the ginger beer owed Mrs. Donoghue a duty of care under this principle:
"You must take reasonable care to avoid acts or omissions which you can reasonably foresee would be likely to injure your neighbour."
The full text of the case can be found here.
-  A.C. 562 Page 580