In Sebastian Hiriart v. Jean Gassies Ballon, the plaintiff in error argued that he had a valid claim to certain property located in Louisiana. The defendant maintained that the title was invalid because it did not meet all of the requirements set forth by Spanish law at the time of its issuance. After reviewing both parties' arguments, the Supreme Court held that while there were some discrepancies with regard to how and when title was granted, they could not be used as grounds for denying validity due to lack of evidence or proof from either party. Ultimately, they ruled in favor of Mr. Hiriart's claim and found his title valid under Spanish law at the time it was issued.

In this case, the Supreme Court was asked to decide whether a contract between two parties should be enforced. The plaintiff argued that he had entered into an agreement with the defendant in which they agreed to exchange land and money for cattle. However, when it came time to fulfill his part of the bargain, the defendant refused. The majority opinion held that since there was no written evidence of their agreement, it could not be enforced by law. Justice McLean dissented from this decision and argued that even though there was no written record of their agreement, both parties had acted as if one existed and thus should be bound by its terms. He further stated that contracts do not need to have been reduced to writing in order for them to be enforceable under law; rather they can also exist through verbal agreements or other forms of communication such as letters or telegrams.