Haver v. Yaker was a United States Supreme Court case that dealt with the issue of whether a contract between two parties was valid. The case involved a contract between two individuals, Haver and Yaker, in which Haver agreed to pay Yaker a certain sum of money in exchange for Yaker's promise to perform certain services. Yaker failed to perform the services, and Haver sued for breach of contract. The Supreme Court held that the contract between Haver and Yaker was valid and enforceable. The Court reasoned that the contract was supported by consideration, meaning that each party had given something of value in exchange for the other's promise. The Court also held that the contract was not void for lack of mutuality, meaning that both parties had an obligation to perform under the contract. The Court's decision in Haver v. Yaker established that a contract between two parties is valid and enforceable if it is supported by consideration and is not void for lack of mutuality. This decision has been cited in numerous subsequent cases and has become an important part of contract law in the United States.

In Haver v. Yaker, the Supreme Court was asked to decide whether a state court had jurisdiction over an action brought by a non-resident against another non-resident in regards to property located within the state. The majority opinion held that such actions were not within the scope of the state court's jurisdiction and must be heard in federal courts instead. Justice Field dissented from this decision, arguing that it would lead to unnecessary delays and costs for parties involved in litigation as they would have to litigate their cases twice - once at the state level and then again at federal level if either party disagreed with the outcome of first trial. He further argued that allowing states courts jurisdiction over these types of cases is consistent with other areas of law where Congress has granted concurrent powers between both levels of government without requiring double trials on same issues.