A legal principle under which a person should not be obliged to pay, nor should another be allowed to receive, more than the value of the goods or services exchanged; hence, as much as is deserved only.
Closely related to the equitable concept of unjust enrichment, quantum meruit is often claimed by lawyers, for example, where they have performed legal services for a client but neglected to have the client sign a retainer. In asking a court to recognize their bill for services, they fall back on quantum meruit.
Although the existence of a quantum meruit remedy does not depend on a contract, it is also a remedy in contract law where a contract has been breached but after one side received partial or full benefit, and the contract does not include a clause providing for this eventuality (such as a liquidated damages clause).
In Litemore, Justice Read borrows from Fridman's 2nd edition of Restitution, which waxes thick on the legalese but otherwise provides a comprehensive explanation of quantum meruit as follows:
"Quantum meruit is a separate and distinct cause of action from either contract or tort.
"It is founded upon an obligation imposed by law when there would otherwise be an unjust enrichment of one party at the expense of the other.
"In a contractual setting, remuneration is said to be paid on a quantum meruit basis when, although a valid contract is found to exist in fact and law, there is no clause spelling out in express terms the consideration for the contract. In such circumstances, the courts award reasonable remuneration to the person who has rendered the services.
"In a quasi-contractual setting, an action for quantum meruit is based, in general, upon the rendering of services by one person to another who has requested such services be rendered or freely accepted them with the knowledge that they are not rendered gratuitously... A person should only be called upon to pay for benefits, in general, where he has requested or freely accepted such services with the opportunity to reject. It is not sufficient that the plaintiffs have rendered the services under a mistake. He must go further and show that the services were requested or freely accepted by the defendant."
In Bond Development (2006), a Canadian court summarized the term as follows:
"A claim for quantum meruit is for reasonable remuneration for the services provided, the amount it deserves or what the job is worth.
"Thus, the trial judge was correct when he noted ... that, '(q)uantum meruit involves consideration of the amount and value of the services rendered, not potential profit.' The amount to which a plaintiff is entitled on the basis of unjust enrichment is the value of the benefit obtained by the defendant, and not the loss to the plaintiff assessed as if the contract were fulfilled."
In Pavey & Matthews Pty Ltd v Paul 162 C.L.R. 221 (1987), the High Court of Australia stated that an action could be brought on a quantum meruit to recover reasonable remuneration for work done under an otherwise unenforceable contract.