Ex Post Facto Law.

This article examines the concepts of retrospective and retroactive—both forms of ex post facto—law. It shows that although the distinction between retrospective and prospective law is difficult to draw (given that laws generally alter rights), the classification of particular laws as retrospective is not arbitrary, since the proposition that only some legal rules interfere with “vested” rights is, while vague, not meaningless. Retroactive legislation is recognized to attract a long list of objections. The article seeks to identify and assess those objections, and to provide a comprehensive account of the various possible (if invariably limited) justifications for retroactivity. The conclusion offers some brief reflections on why the complaint that a law operates ex post facto is less likely to be directed at a judicial decision than at a statute. [ABSTRACT FROM AUTHOR]