Abstract

It can be compatible with justice and the rule of law for a court to impose new legal liabilities retrospectively on a defendant. But judges do not need to distinguish between imposing a new liability, and giving effect to a liability that the defendant had at the time of the events in dispute. The distinction is to be drawn by asking which of the court's reasons for decision the institutions of the legal system had already committed the courts to act upon, before the time of decision. I explain these conclusions through an assessment of the last episode in the debate between H.L.A.Hart and Ronald Dworkin