Illegal agreement

An illegal agreement, under the common law of contract, is one that the court will not enforce because either (1) the making of the agreement itself is illegal or (2) the agreement becomes illegal because of the way in which it is performed. The classic example of such an agreement is an agreement to commit a crime. For example, entering into a contract for murder is itself illegal because that very act can be prosecuted as the crime of conspiracy to commit a murder. Ewan McKendrick notes that contracts which are "contrary to public policy" are often referred to, for ease, as "illegal" contracts".

The illegality of a contract depends on the law of the jurisdiction governing the contract, and the law of the place of performance: different rules will apply depending on the laws of the relevant jurisdictions.

However, a contract that requires only legal performance on the part of each party, such as the sale of packs of cards to a known gambler, where gambling is illegal, will nonetheless be enforceable. A contract directly linked to the gambling act itself, such as paying off gambling debts (see proximate cause), however, will not meet the legal standards of enforceability. Therefore, an employment contract between a blackjack dealer and a speakeasy manager, is an example of an illegal agreement and the employee has no valid claim to his anticipated wages if gambling is illegal under that jurisdiction.