retroactive law
retroactive law 有追溯力的法律 效力及于其生效以前所发生的事件和行为的法律。在美国这一法律并非违宪，除非：１具有对当事人不利的追溯既往效力〔ex post facto〕或者剥夺公民权法案〔bill of attainder〕的性质；２损害合同义务；３剥夺已赋予的权利；４为宪法所禁止。
RETROACTIVE LAW
retroactive law
retroactive law. A legislative act that looks backward or contemplates the past, affecting acts or facts that existed before the act came into effect. • A retroactive law is not unconstitutional unless it (1) is in the nature of an ex post facto law or a bill of attainder, (2) impairs the obligation of contracts,