Common lawyers have long shown a remarkable reluctance to impose criminal liability for omissions. Such liability, it has recently been said, is ‘uncongenial’ — and this seems to be right. Even where the law does, in reality, impose liability for omissions we find courts and writers trying to explain the phenomenon on some other ground. The feeling seems to be that, because the imposition of liability for an omission implies a duty to act it is an interference with the liberty of a person who wishes only to mind his own business and let others get on with minding theirs. Moreover omissions do not cause evil results in the same obvious sense as acts.