Jacks v. Helena was a United States Supreme Court case that addressed the issue of whether a state could tax the income of a non-resident. The case was brought by a resident of the state of Montana, who was employed by a company based in the state of Arkansas. The plaintiff argued that the state of Montana had no right to tax his income, as he was not a resident of the state. The Supreme Court ultimately ruled in favor of the plaintiff, holding that a state cannot tax the income of a non-resident. The Court reasoned that the power to tax is an attribute of sovereignty, and that a state cannot exercise its power of taxation beyond its own borders. The Court further held that the power to tax is limited to the state's own citizens, and that a state cannot tax the income of a non-resident. The Court's decision in Jacks v. Helena established the principle that a state cannot tax the income of a non-resident.

Justice Field delivered the dissenting opinion in Jacks v. Helena, arguing that the city of Helena had not violated any constitutional rights by refusing to pay a debt owed to plaintiff William Jacks. He argued that while it was true that there were contracts between Jacks and the city for certain services, those contracts did not create an obligation on behalf of the city to pay him if he failed to perform his duties as agreed upon. Furthermore, Justice Field noted that even if such an obligation existed, it would be unenforceable due to sovereign immunity protections enjoyed by states and municipalities under federal law. As such, he concluded that no legal remedy could be provided for Jacks' claim against Helena and thus affirmed its decision denying payment of his debt.