Garratt v. Seibert 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 dispute between two parties, Garratt and Seibert, over a contract for the sale of a piece of land. Garratt had agreed to purchase the land from Seibert for a certain amount of money, but Seibert later refused to accept the payment and instead demanded a higher price. Garratt then sued Seibert for breach of contract. The Supreme Court held that the contract between the two parties was valid and enforceable. The Court found that the contract was supported by consideration, meaning that both parties had given something of value in exchange for the other's promise. The Court also found that the contract was not voidable due to any fraud or misrepresentation on the part of either party. Ultimately, the Supreme Court held that the contract between Garratt and Seibert was valid and enforceable, and that Seibert was liable for breach of contract. The Court ordered Seibert to pay Garratt the amount of money that had been agreed upon in the contract. This case established the principle that contracts are binding and enforceable, and that parties must abide by the terms of the contract that they have agreed to.

In the case of Garratt v. Seibert, Justice Field delivered a dissenting opinion in which he argued that the majority's decision was wrongfully based on an interpretation of state law rather than federal law. He believed that the court should have applied federal common law to this dispute and not relied solely on state statutes. According to Justice Field, it was necessary for the Court to consider both sources of authority when deciding cases involving interstate commerce because Congress had granted exclusive power over such matters to itself under Article I, Section 8 of the Constitution. Furthermore, he noted that if courts were allowed to rely exclusively on state laws in these types of disputes then they would be effectively overruling congressional intent by allowing states' rights precedence over national interests. In conclusion, Justice Field maintained his belief that federal common law must be considered alongside applicable state laws when determining questions related to interstate commerce so as not interfere with Congressional powers outlined in Article I, Section 8