EX POST FACTO LAW

law that purports to retroactively make criminal a certain conduct that was not criminal when done, increases the punishment for crimes already committed, or changes the rules of procedure in force at the time an alleged crime was committed in a way substantially disadvantageous to the accused. In the United States, the Constitution forbids Congress and the states to pass any ex post facto law. In 1798 it was settled that this prohibition applies only to criminal laws and is not a general restriction on retroactive legislation. Implicit in the prohibition is the notion that individuals be punished only in accordance with standards of conduct they might have ascertained before acting. The clause also serves, in conjunction with the bill-of-attainder clause, as another safeguard against the historic practice of passing laws to punish particular individuals because of their political beliefs. In 1867, in Cummings v. Missouri and Ex parte Garland, the loyalty-test oaths passed after the American Civil War to keep Confederate sympathizers from practicing certain professions, although not really criminal statutes, were condemned both as bills of attainder and as ex post facto laws. The policies underlying ex post facto laws are recognized in most developed legal systems. They are reflected in the civil law maxim nulla poena sine lege (no punishment without law), a principle whose roots can be found in Roman law. In England, where Parliament is not prohibited from passing ex post facto laws, the judges, in accord with common-law tradition, have refused to interpret legislation retroactively unless Parliament has clearly expressed such an intention. Prosecution of Nazi leaders following World War II for the crime of aggressive war (a crime specifically defined for the first time in the Allied charter creating the International Military Tribunal for war criminals) provoked extensive discussion over the scope and applicability of the principle against retroactive criminal laws.