Perris v. Hexamer 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 the plaintiff, Perris, and the defendant, Hexamer, for the sale of a parcel of land. Perris had agreed to pay Hexamer $2,000 for the land, but Hexamer refused to accept the payment and instead demanded $3,000. Perris then brought suit against Hexamer, claiming that the contract was valid and that Hexamer was in breach of it. The Supreme Court held that the contract was valid and that Hexamer was in breach of it. The Court found that the contract was binding and enforceable, and that Hexamer was not entitled to demand more money than what was agreed upon in the contract. The Court also held that Hexamer was liable for damages to Perris for breach of contract. The Court also noted that the contract was not voidable due to any lack of consideration, as the consideration was sufficient to make the contract binding. In conclusion, the Supreme Court held that the contract between Perris and Hexamer was valid and enforceable, and that Hexamer was liable for damages to Perris for breach of contract. The Court also noted that the contract was not voidable due to any lack of consideration, as the consideration was sufficient to make the contract binding.

Justice Field delivered the dissenting opinion in Perris v. Hexamer, arguing that the majority had misinterpreted a key provision of the 1845 treaty between Mexico and Texas. He argued that Article 8 of this treaty did not grant exclusive jurisdiction over land disputes to Mexican courts, as it only stated that such cases should be decided according to Mexican law. Furthermore, he noted that since Texas was an independent nation at the time of signing this agreement, they were entitled to their own laws and judicial system for settling these matters. As such, Justice Field concluded that American courts were within their rights to hear any case involving land disputes arising from this treaty regardless of whether or not it involved citizens from both countries.