Mackall v. Richards & Another 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 Mackall and Richards, in which Mackall agreed to pay Richards a certain amount of money for the sale of a piece of property. Mackall failed to make the payment, and Richards sued for breach of contract. The Supreme Court held that the contract was valid and enforceable. The Court found that the contract was supported by consideration, meaning that both parties had given something of value in exchange for the agreement. The Court also found that the contract was not void for lack of consideration, as Mackall had promised to pay a certain amount of money for the property. The Court also held that Mackall was liable for breach of contract, as he had failed to make the payment as promised. The Court found that Mackall had not provided any valid excuse for his failure to make the payment, and thus he was liable for breach of contract. In conclusion, the Supreme Court held that the contract between Mackall and Richards was valid and enforceable, and that Mackall was liable for breach of contract for failing to make the payment as promised.

In the case of Mackall v. Richards & Another, Justice Field delivered a dissenting opinion in which he argued that the majority's decision was incorrect and should be reversed. He noted that under Maryland law, an executor or administrator is not liable for debts incurred by their predecessor unless they expressly assume them. In this case, there was no evidence to suggest that Richards had assumed any such debt when he took over as executor from his father-in-law; thus, it would have been improper to hold him responsible for those debts. Furthermore, Field argued that even if Richards had agreed to pay off these debts at some point in time prior to taking on the role of executor (which again there was no evidence of), then it would still be inappropriate for him to be held liable since he did not agree with specific knowledge of what those obligations were or how much money needed to be paid out. Thus, Justice Field concluded that the lower court's ruling should stand and Mackall's claim against Richards should fail due solely lack of proof regarding assumption liability on behalf of Richard’s part