The doctrine of implied repeal is a concept in constitutional theory which states that where an Act of Parliament or an Act of Congress (or of some other legislature) conflicts with an earlier one, the later Act takes precedence and the conflicting parts of the earlier Act become legally inoperable. This doctrine is expressed in the Latin phrase leges posteriores priores contrarias abrogant or "lex posterior derogat priori".
Implied repeal is to be contrasted with the express repeal of legislation by the legislative body.