Smith et al. v. United States was a case heard by the U.S Supreme Court in 1864 that dealt with the issue of whether or not an individual could be held liable for debts incurred during their service in the military, even if they had been discharged from duty before those debts were due to be paid off. The court ultimately ruled against Smith and his co-defendants, finding that they were indeed responsible for any debt accrued while serving in the military, regardless of when it became payable after discharge from service. This decision set a precedent which has since been used to hold individuals accountable for financial obligations taken on during their time as members of the armed forces, even if those obligations are not fulfilled until after leaving active duty status.

In Smith et al. v. United States, the Supreme Court ruled in favor of the United States and against the petitioners, who were a group of individuals from Virginia convicted under an act passed by Congress that prohibited citizens from engaging in insurrectionary activities during wartime. The majority opinion held that Congress had acted within its constitutional authority to pass laws necessary for carrying on war when it enacted this statute, which was intended to protect Union forces operating in Confederate-held territory. Justice Field dissented from this ruling and argued that while he agreed with the majority's conclusion regarding Congressional power over military affairs during times of war, he believed that such power should not be used as a means to punish civilians for their political beliefs or actions taken before hostilities began between two nations or states. He further argued that if Congress could use its powers over military matters as a way to punish civilians for acts committed prior to any declaration of war then it would have too much control over individual liberty and freedom without due process protections being provided first by judicial review or other legal safeguards established beforehand.