This case was between Pierre Chouteau, Sen. and William Eckhart. The dispute arose from a contract made in 1837 for the sale of goods by Eckhart to Chouteau. In 1840, Chouteau sued for breach of contract claiming that he had not received all the goods promised under the agreement and sought damages as well as an injunction against further sales of those same items by Eckhart to other parties. The lower court found in favor of Chouteau but awarded him only nominal damages due to his failure to mitigate losses resulting from the breach. On appeal, however, it was determined that since there were no mitigating circumstances present at trial which could have reduced or eliminated any potential damage award then full compensation should be granted instead; thus reversing and remanding with instructions for a new trial on this issue alone. Ultimately this decision established precedent regarding mitigation requirements when seeking damages related to contractual breaches within US courts

In the case of Pierre Chouteau, Sen., Plaintiff in Error v. William Eckhart, the Supreme Court was tasked with determining whether a contract between two parties had been breached. The plaintiff argued that he had entered into an agreement to purchase certain goods from the defendant and that payment for those goods had not been made as agreed upon. The majority opinion held that there was no breach of contract because it could not be proven beyond reasonable doubt that any such agreement existed in writing or otherwise. However, Justice McLean dissented on this point and argued instead that sufficient evidence did exist to prove a valid contract between the two parties; namely, testimony from witnesses who were present when the alleged agreement was reached as well as other circumstantial evidence which pointed towards its existence. He further contended that even if some uncertainty remained regarding certain details of said agreement, it should still be considered binding due to principles of equity and fairness under common law precedent established by prior cases involving similar circumstances.