In Foster v. Mora, the Supreme Court of the United States was asked to decide whether a contract between two parties was valid and enforceable. The contract in question was between Foster, a resident of New Mexico, and Mora, a resident of California. The contract stated that Foster would pay Mora a certain sum of money in exchange for Mora's promise to deliver a certain quantity of goods to Foster. The Supreme Court held that the contract was valid and enforceable. The Court noted that the contract was made in good faith and that both parties had the capacity to enter into the contract. The Court also noted that the contract was not against public policy and that it was not illegal. The Court further held that the contract was binding on both parties and that Foster was entitled to the goods promised by Mora. In conclusion, the Supreme Court held that the contract between Foster and Mora was valid and enforceable. The Court noted that the contract was made in good faith and that both parties had the capacity to enter into the contract. The Court also held that the contract was binding on both parties and that Foster was entitled to the goods promised by Mora.

Justice Field delivered the dissenting opinion in Foster v. Mora, arguing that the majority's decision was inconsistent with prior Supreme Court precedent and undermined Congress' authority to regulate public lands. He argued that while a state may have jurisdiction over its own land, it does not necessarily follow that they can exercise control over federal property within their borders. Furthermore, he noted that if states were allowed to do so without congressional approval, then this would lead to confusion and chaos as each state could pass different laws governing the same piece of land. As such, Justice Field concluded by asserting his belief that only Congress has the power to make laws regulating public lands held by the United States government.