Coddington v. Richardson was a United States Supreme Court case that dealt with the issue of whether a state could tax the income of a non-resident. The plaintiff, Coddington, was a resident of New York who owned property in the state of Connecticut. The defendant, Richardson, was the Collector of Taxes for the state of Connecticut. Coddington argued that the state of Connecticut had no right to tax his income from the property he owned in the state, as he was a non-resident. The Supreme Court ruled in favor of Coddington, holding that the state of Connecticut could not tax the income of a non-resident. The Court reasoned that the power to tax income was a power reserved to the states, and that the state of Connecticut had no authority to tax the income of a non-resident. The Court further held that the state of Connecticut could not impose a tax on the income of a non-resident without violating the privileges and immunities clause of the Fourteenth Amendment. The decision in Coddington v. Richardson established that states cannot tax the income of non-residents, and that such taxation would violate the privileges and immunities clause of the Fourteenth Amendment. This decision has been cited in numerous subsequent cases, and has been used to protect the rights of non-residents from taxation by states.

In Coddington v. Richardson, the Supreme Court was asked to decide whether a state court had jurisdiction over an action brought by a citizen of one state against another in which the defendant resided in yet another state. The majority opinion held that it did not have such jurisdiction and dismissed the case. Justice Field dissented from this decision, arguing that under Article III of the Constitution, Congress has given federal courts exclusive original jurisdiction over controversies between citizens of different states and therefore any other court would lack authority to hear such cases unless authorized by Congress or provided for in some treaty or convention with foreign powers. He further argued that since no such authorization existed here, then only federal courts could hear this case and thus he disagreed with his colleagues' ruling on jurisdictional grounds.