Abstract

The defence of necessity has had a long, though confused, legal career. Like self-defence, consent, duress, insanity and mistake of law, necessity is rooted in moral intuitions about when conduct which causes harm to another's person or property is not wrong, or should be tolerated, permitted or praised. If a man is literally starving to death and steals a loaf of bread, we are reluctant to say that his extreme circumstances should make no difference at all to the way we treat him at trial. And if two men, adrift at sea, are clinging to a log which can only support the weight of one, we are once again reluctant to say that if one pushes the other off the log, it is just a case of murder. These intuitions are deepseated; but it is extremely difficult to articulate the defence they seem to support, or to isolate the circumstances which mark the difference between a situation where the defence ought to apply and where it ought not.