A purchaser of land under an oral contract, who is given possession and subsequently fails to pay, is liable for the use of the land to him while he has occupied it. Though the act of the seller in giving the purchaser possession without conveying the title may not be regarded as a part performance of the contract of sale, yet the benefit resulting to the purchaser creates an obligation to make restitution which the courts will enforce. The improvement of land by the purchaser under an oral contract is an act which enables him to enforce the contract in equity. Improvements made by a lessee under an oral lease within the statute are governed by the same rules as those of improvements made by a purchaser.
If no benefit has been derived from the contract, nothing can be recovered. Thus, a son worked for his father on his father's farm under an unenforceable contract with his uncle. The latter was under no quasi contractual obligation to pay the value of such service, since he had derived no benefit from them. Likewise one who, relying on an unenforceable contract, constructed a wood-chopping machine that was not accepted could not recover for the value of his labor and materials.
Again, where one party by his own act or default has prevented the other party from fully performing his contract, the party thus preventing performance cannot take advantage of his own act or default, and screen himself from payment for what has been done under the contract. Thus, if one party agrees with another to work on a house the law implies that the employee owns the building in which the work is to be done. This is a part of the contract whether the house is clearly specified or not. Therefore, an employer who does not own the house, or parts with it before the work is completed, is liable to the other party.
The destruction of a thing in the course of alteration or repair without the fault of the bailee is a case like that above mentioned. The labor and materials are expended in response to the desire of the owner of the property, and therefore it is just that he should pay for the property he destroyed. In one of the old cases a horse was sent to a farrier to be cured and was burnt before a cure was completely effected. Nevertheless, the farrier was entitled to payment for what he had done. Likewise, the owner of a ship that is destroyed by fire a few hours before the completion of repairs, cannot escape payment on the ground that he has reaped no advantage.