Morsell et al. v. First National Bank was a case heard by the United States Supreme Court in 1875. The case involved a dispute between the First National Bank of Baltimore and the heirs of a deceased man, John Morsell. The bank had loaned money to Morsell and had taken a mortgage on his property as security for the loan. After Morsell's death, the bank attempted to foreclose on the property, but the heirs argued that the bank had no right to do so because the mortgage was invalid. The Supreme Court held that the mortgage was valid and that the bank had the right to foreclose on the property. The Court reasoned that the mortgage was valid because it had been properly executed and recorded in accordance with the laws of Maryland. The Court also held that the bank had the right to foreclose on the property because it had a valid security interest in the property. The Court's decision in this case established the principle that a mortgage is valid if it is properly executed and recorded in accordance with the laws of the state in which it is located. This principle has been applied in numerous cases since then and is still the law today.

In Morsell et al. v. First National Bank, the Supreme Court was tasked with determining whether a bank could be held liable for failing to pay out on an insurance policy that had been assigned by its original owner to another party without the bank's knowledge or consent. The majority opinion found in favor of the bank, holding that it did not have any legal obligation to honor such an assignment and thus could not be held liable for refusing payment. Justice Field dissented from this decision, arguing that since banks are expected to exercise reasonable care when dealing with customers' funds and property, they should also be required to take reasonable steps in order ensure that assignments of policies are valid before denying payments on them. He further argued that if banks were allowed off the hook so easily then there would be no incentive for them to properly investigate these types of transactions and protect their customers from fraud or other illegal activities related thereto.