A consequentialist holds that systems of criminal punishment must be justified, if they can be justified at all, by their consequential benefits. It is a contingent fact, if it is a fact at all, that these benefits are most efficiently attained by a system of punishment, and by punishments which ordinary moralists would regard as just; and a thorough-going consequentialist must be ready in principle to justify punishments which many would condemn as unjust. A retributivist, on the other hand, insists that the justice of a system or instance of punishment is essential to its justification; and that the demands of justice cannot be reduced to those of consequential utility.
Retributivist accounts of punishment come in a variety of forms: we must distinguish those who insist only that guilt is a necessary, not a sufficient, condition of justified punishment from those who insist that punishment must be fully justified by reference to a past offence; and amongst the latter we find various accounts of how it is that an offence justifies or requires punishment. But essential to any retributivist account is the claim that an adequate justification of punishment must cite not, or not only, its consequential benefits, but its relationship to a past offence: it is a non-consequentialist requirement of justice that punishment must be of an offender, for an offence; that only the guilty may be punished, and that the severity of their punishments should be limited, if not completely determined, by the seriousness of the offences for which they are punished.