In all contracts, whether nominate or innominate, an exchange [of value, i.e., a consideration] is implied.

Explanation

(English-origin maxim.) Every contract, whether named or unnamed, must be supported by consideration — an exchange of value is the essential element that distinguishes a binding agreement from a bare promise.

Where this applies

• A contractor argues that his handshake deal with a homeowner is not a real contract because no money changed hands, but the court finds the mutual exchange of promises constitutes consideration.
• A barter agreement where one party trades carpentry work for accounting services is a valid contract because the exchange of value — consideration — is implied in every contract.
• Two neighbors agree that one will mow the other's lawn in exchange for snow plowing — even without money, the exchange of services is the consideration that makes the agreement binding.