The Collaborative International Dictionary
Retroactive statute
Retroactive \Re`tro*act"ive\, a. [Cf. F. r['e]troactif.]
Fitted or designed to retroact; operating by returned action;
affecting what is past; retrospective.
--Beddoes.
Retroactive law or Retroactive statute (Law), one which operates to make criminal or punishable, or in any way expressly to affect, acts done prior to the passing of the law.