Clements v. Moore was a United States Supreme Court case that dealt with the issue of whether a state could tax the property of a non-resident. The case was brought by a resident of the state of Missouri, who owned property in the state of Arkansas. The plaintiff argued that the state of Arkansas had no right to tax his property, 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 property 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 an attribute of sovereignty, and that a state cannot exercise its power of taxation beyond its own borders. This decision established the principle that a state cannot tax the property of a non-resident, and has been cited in numerous subsequent cases.

In Clements v. Moore, the Supreme Court was asked to decide whether a state court had jurisdiction over a case involving an alleged breach of contract between two citizens of different states. The majority opinion held that the state court did not have jurisdiction because it violated the Constitution's requirement for full faith and credit among states. Justice Field dissented from this decision, arguing that there was no constitutional prohibition against allowing one state to exercise jurisdiction in such cases when both parties were citizens of different states. He argued further that Congress had not prohibited such action by statute either, so it should be allowed as long as all other requirements for exercising jurisdiction were met. In conclusion, he believed that if Congress wanted to restrict or prohibit this type of jurisdictional authority then they should do so explicitly rather than leaving it up to judicial interpretation and inference from existing laws and precedents.