Laesio enormis

Laesio enormis (Latin: abnormal harm) is a legal doctrine that gives a contracting party the ability to rescind an agreement if the price of exchange is less than a certain proportion (for instance one half, or two thirds) of its actual value. The principle was developed as a way to ensure that people received a just price (iustum pretium) in exchange, and in opposition to the Imperial Roman view, found in the Corpus Juris Civilis,^[1] that the parties to an exchange were entitled to try to outwit one another.