Drakely v. Gregg was a United States Supreme Court case that dealt with the issue of whether a state could require a non-resident to pay a tax on the income they earned within the state. The case was brought by a resident of Pennsylvania, who had earned income in the state of Maryland. The state of Maryland had imposed a tax on the income earned by non-residents, and the plaintiff argued that this was unconstitutional. The Supreme Court ultimately ruled in favor of the state of Maryland, finding that the tax was not unconstitutional. The Court reasoned that the tax was a legitimate exercise of the state's power to regulate commerce within its borders, and that it did not violate the privileges and immunities clause of the Constitution. The Court also noted that the tax was not discriminatory, as it applied equally to both residents and non-residents. In conclusion, the Supreme Court held that the state of Maryland had the right to impose a tax on the income earned by non-residents within its borders. The Court found that the tax was a legitimate exercise of the state's power to regulate commerce, and that it did not violate the privileges and immunities clause of the Constitution.

In Drakely v. Gregg, the Supreme Court was asked to decide whether a state court had jurisdiction over a case involving federal land located in that state. The majority opinion held that the state court did have jurisdiction and could hear the case. However, Justice Field dissented from this decision, arguing that it violated Article III of the Constitution which states that only federal courts can exercise judicial power over cases arising under laws of Congress or treaties made by them. He argued further that if states were allowed to exercise such powers then they would be able to override any decisions made by Congress on matters concerning public lands within their borders and thus undermine congressional authority. Furthermore, he noted how allowing such actions could lead to conflicting interpretations between different states regarding issues related to federal law and create confusion among citizens who may not know which court has jurisdiction over their particular dispute.