Adjudication and the Law

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