Genres v. Campbell was a United States Supreme Court case that dealt with the issue of whether a state could constitutionally require a non-resident to pay a tax on the income they earned within the state. The case was brought by a resident of New York, who had earned income in the state of Ohio. The Ohio state legislature had passed a law requiring non-residents to pay a tax on income earned within the state. The plaintiff argued that this law was unconstitutional, as it violated the privileges and immunities clause of the Fourteenth Amendment. The Supreme Court ultimately ruled in favor of the plaintiff, finding that the Ohio law was unconstitutional. The Court held that the privileges and immunities clause of the Fourteenth Amendment prohibited states from discriminating against non-residents in the taxation of their income. The Court reasoned that the clause was intended to protect the rights of citizens of one state when they travel to another state, and that the Ohio law violated this principle. The Court also noted that the law was not necessary to protect the interests of the state, as the state could have imposed a tax on all income earned within its borders, regardless of the residence of the taxpayer. In conclusion, the Supreme Court held that the Ohio law was unconstitutional, as it violated the privileges and immunities clause of the Fourteenth Amendment. The Court's decision established an important precedent, as it affirmed the principle that states cannot discriminate against non-residents in the taxation of their income.

In Genres v. Campbell, 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 amount in controversy exceeded $500. The majority opinion held that it did not have such jurisdiction and reversed the decision of the lower court. Justice Field dissented from this ruling, arguing that under Article III of the Constitution, Congress has granted all courts established by states authority to hear cases involving citizens from different states when more than $500 is at stake. He argued further that if Congress had intended for federal courts alone to have exclusive jurisdiction over these types of cases then they would have explicitly stated so in their legislation or made some other provision for it. In his view, since no such language exists then there is no reason why state courts should be denied access to them as well.