In Mandeville v. The Union Bank of Georgetown, the Supreme Court considered a case involving an alleged breach of contract between two parties. The plaintiff, William Mandeville, had loaned money to the defendant bank and was seeking repayment with interest. However, the bank argued that it was not liable for any damages because its charter did not allow it to make such loans in the first place. After considering both sides’ arguments, Chief Justice John Marshall held that although banks are generally prohibited from making loans outside their charters' scope by state law or other regulations, they can still be held responsible for contracts made in good faith if there is no evidence of fraud or bad faith on either side's part. He further stated that when a party enters into a contract without knowledge of any restrictions imposed upon them by law or regulation then they should be bound to fulfill their obligations under said agreement regardless if those obligations exceed what would normally be allowed under said laws and regulations.

In Mandeville v. The Union Bank of Georgetown, the Supreme Court was tasked with determining whether a bank could be held liable for failing to pay out on a note that had been endorsed by an individual who had since died. Justice Story delivered the dissenting opinion in this case, arguing that it would be unjust and inequitable to hold the bank responsible for honoring such notes when they were not aware of any potential risks associated with them at the time of their endorsement. He further argued that if banks were required to honor all notes regardless of their endorsers' death or insolvency, then it would create an undue burden on them and ultimately lead to financial instability within society as a whole. Ultimately, he concluded that while there may have been some negligence involved in this particular instance due to lack of knowledge about the endorser's status at the time, holding banks accountable for such matters should only occur after proper investigation into each case has taken place so as not to unfairly punish those institutions which acted in good faith but without full information available at hand.