Where it is unclear whether a duty of care exists, it is possible to go back to the famous case of Donoghue v. Stevenson  AC 562. In this case, a woman became very ill after having consumed the contents of a ginger beer bottle. The ginger beer bottle was found to contain the remains of a decomposed snail. Lord Atkin, in considering whether the manufacturer of the ginger beer bottle owed a duty of care to people who might drink its contents, put forward what is known as the 'neighbour principle':
'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.'