Abstract
The article analyses the institute of laesio enormis and its nature in the Czech Civil Code. Based on a historic overview, there is presented its development and philosophical background that can be found in the idea of the just price which has been considered an imperative of commutative justice.
After the end of the Middle Ages, the concept of just price was heavily criticized for its alleged contradiction with contractual freedom and legal certainty. Nevertheless, the great civil law codifications in France and Austria encompassed laesio enormis.
The regulation of laesio enormis in most modern civil codes (e.g. in Netherlands, Italy, or Switzerland), however, significantly resembles usury. The Czech Civil Code, which reintroduced laesio enormis to our legal system after more than sixty years, reflects the same trend.
The prohibition of laesio enormis is conditioned by the fulfillment of a subjective feature: the injured party must not know the real price while the other party must know (or be required to know) a fact the disproportion is based on. Therefore, this regulation protects the party with less information rather than an abstract just price.