Welch v. Mandeville was a case heard by the United States Supreme Court in 1812. The dispute arose when William Welch, an attorney from New York, sued John Mandeville for failing to pay him $1,000 that had been awarded to him as part of a judgment against another party. In his defense, Mandeville argued that he should not be held liable because the original judgment did not specify who was responsible for paying the debt and thus it could not be enforced against him personally. The Supreme Court disagreed with this argument and ruled in favor of Welch, holding that even though there may have been some ambiguity regarding who was obligated to pay the debt under the original judgment, it still created an enforceable obligation on all parties involved which included both Welch and Mandeville. As such they found that since no other person had paid off this debt then it fell upon Mandeville himself to do so or else face legal action from Welch for non-payment.

In the case of Welch v. Mandeville, Chief Justice Marshall delivered a dissenting opinion in which he argued that the Court should not have granted an injunction to prevent Mandeville from selling certain goods because it was beyond their jurisdiction. He reasoned that since this dispute arose out of a contract between two private parties, it was up to them and not the court to resolve any issues related thereto. Furthermore, he noted that granting such an injunction would be contrary to established principles of equity as well as public policy; thus, allowing courts to interfere with contractual arrangements could lead down a slippery slope where contracts were no longer respected or enforced by either party involved in them. Ultimately, Chief Justice Marshall concluded that while there may have been some wrong done here on behalf of one party over another, it did not rise to the level necessary for judicial intervention and therefore should remain outside its purview.