In Leggett v. Allen, Assignee, the Supreme Court of the United States was asked to decide whether a debtor could be held liable for a debt that had been assigned to another party. The case involved a debt that had been assigned to the defendant, Allen, by the debtor, Leggett. Leggett argued that he was not liable for the debt because he had assigned it to Allen. The Supreme Court held that Leggett was liable for the debt because the assignment was invalid. The Court reasoned that the assignment was invalid because it was not in writing and was not supported by consideration. The Court also held that the assignment was invalid because it was not made in accordance with the applicable state law. The Court concluded that Leggett was liable for the debt and that Allen was not entitled to recover it from him.

In Leggett v. Allen, Assignee, the Supreme Court was tasked with determining whether a judgment against an assignor of a promissory note could be enforced against the assignee in New York state court. The majority opinion held that it could not because under New York law at the time, such judgments were considered void and unenforceable. Justice Field dissented from this decision on two grounds: firstly, he argued that there was no evidence to suggest that Congress intended for federal courts to interfere with state laws regarding assignments; secondly, he argued that even if Congress had done so in this case by passing legislation allowing suits against assignees of notes like these to proceed in federal court without regard for local laws or customs prohibiting them from doing so, then they would have been unconstitutional as infringing upon states' rights. In conclusion, Justice Field believed that since there was no indication either way as to what Congress's intentions were concerning this issue and since any attempt by them to override existing state laws would have been unconstitutional anyway - then it should be left up to each individual state's legislature (and not the federal government) as how best handle cases involving assignments of notes like these going forward.