In Knox v. Exchange Bank, the Supreme Court of the United States was asked to decide whether a bank could be held liable for the negligence of its employees. The case arose when a customer of the Exchange Bank of Pennsylvania, John Knox, sued the bank for damages after he was injured in a fall caused by the negligence of one of the bank's employees. The Supreme Court held that the bank could be held liable for the negligence of its employees. The Court reasoned that the bank had a duty to exercise reasonable care in the selection and supervision of its employees, and that it had failed to do so in this case. The Court also noted that the bank had a duty to protect its customers from the negligence of its employees, and that it had failed to do so in this case as well. The Court's decision in Knox v. Exchange Bank established that banks can be held liable for the negligence of their employees. This decision has been cited in numerous subsequent cases, and it has become an important precedent in the area of tort law.

In the case of Knox v. Exchange Bank, Justice Field delivered a dissenting opinion in which he argued that the majority had misapplied existing law and failed to consider relevant facts. He noted that under existing precedent, an assignee of a debt could not sue on it unless they were specifically authorized by the original creditor or debtor to do so. In this case, there was no such authorization from either party; therefore, according to Field's interpretation of the law at hand, Exchange Bank should not have been allowed to bring suit against Knox for payment on behalf of its assignor. Furthermore, Field pointed out that even if Exchange Bank had been able to prove their right as an assignee with proper authority from either party involved in the transaction originally (which they did not), then any judgment rendered would still be subject to setoff due to other debts owed by Knox which predated his obligation towards Exchange Bank's assignor - something which was overlooked by both parties during trial proceedings and ignored entirely by the majority opinion.