In the Union National Bank v. Lamb case of 1948, the U.S. Supreme Court ruled in favor of Union National Bank, reversing a decision by the lower court that had favored Lamb. The dispute centered on whether or not a bank could be held liable for honoring checks drawn against insufficient funds without notifying creditors about an account holder's insolvency status. In this case, Mr. Lamb was a creditor to an insolvent company whose checks were honored by Union National Bank despite knowing about its financial situation and having no sufficient funds to cover them at that time. The Supreme Court concluded that while banks have certain obligations towards their depositors under federal law, these do not extend to third-party creditors who are not customers of the bank itself - even if they suffer losses as a result of actions taken by those depositors (in this instance, writing bad checks). Therefore, it found no legal basis for holding Union National Bank responsible for any damages incurred by Mr. Lamb due to his debtor's insolvency.

In the dissenting opinion for Union National Bank v. Lamb, Justice Jackson argued that the majority's decision to allow a bank to recover funds from an innocent third party who had received them in good faith was unjust and against established legal principles. He contended that it was unreasonable to expect this individual, who had no knowledge of any wrongdoing or irregularity, to bear the loss caused by another person's fraud. Furthermore, he pointed out that banks have greater resources and expertise than ordinary individuals when it comes to detecting fraudulent transactions and should therefore be held responsible for their own failure in this regard. In his view, shifting the burden onto unsuspecting third parties would undermine public confidence in banking institutions and could potentially lead to widespread financial instability.