A theory of punishment should give some account of mercy and yet it is true to say that very little has been said about it at all. It is commonly regarded as a praiseworthy element in moral behaviour—something to be practised occasionally both for the good of the one who punishes and the one who is punished. The suffering that punishment involves is unpleasant for all concerned, and if it is possible to avoid it or lessen it without moral injustice, then it is desirable to do so. We condemn as hard and unbending the judge who never shows mercy and the suggestion is that the poor unfortunates whose lot it is to be judged by him are poor unfortunates indeed. This is reflected in the fact that the opposite of merciful—merciless—means cruel. Presumably there are occasions when it is appropriate to show mercy to an offender, and other occasions when it is not. What are the conditions for the appropriate exercising of mercy, how do we decide how much mercy is appropriate, and when is a judge morally obliged to be merciful, if ever?