Mohr v. Manierre was a United States Supreme Court case that addressed the issue of whether a contract between two parties was valid. The case involved a contract between a man named Manierre and a woman named Mohr. Manierre had agreed to pay Mohr a certain sum of money in exchange for her services. However, Manierre failed to pay the agreed-upon amount. Mohr sued Manierre for breach of contract. The Supreme Court held that the contract was valid and enforceable. The Court noted that the contract was not void for lack of consideration, as Manierre had promised to pay Mohr a certain sum of money in exchange for her services. The Court also noted that the contract was not void for lack of mutuality, as Manierre had agreed to pay Mohr a certain sum of money and Mohr had agreed to provide her services. The Court held that Manierre was liable for breach of contract and ordered him to pay Mohr the agreed-upon sum of money. The Court also noted that Manierre was not entitled to any set-off or counterclaims, as he had failed to pay the agreed-upon amount. This case established that a contract between two parties is valid and enforceable, even if one party fails to pay the agreed-upon amount.

In the case of Mohr v. Manierre, the Supreme Court was tasked with determining whether a contract between two parties could be enforced when it had been made without consideration and in violation of an existing statute. The majority opinion held that since there was no consideration for the contract, it could not be enforced by either party. However, Justice Field dissented from this decision on the basis that although there may have been no consideration given at all for making such a contract, both parties should still be bound to its terms due to their mutual agreement and understanding of what they were entering into. He argued that if one party is allowed to break their promise simply because there was no exchange of value or goods involved then this would lead to unfairness and injustice as well as encourage dishonesty among those who enter into contracts in good faith but are unable to enforce them later on due to lack of legal protection.