The Wren case was a United States Supreme Court case that dealt with the issue of whether a state could tax the federal government. The case arose when the state of Virginia attempted to impose a tax on the federal government for the use of a lighthouse in the state. The federal government argued that the tax was unconstitutional, as it violated the Supremacy Clause of the Constitution. The Supreme Court ultimately ruled in favor of the federal government, holding that the state could not tax the federal government. The Court reasoned that the Supremacy Clause of the Constitution prohibited the state from taxing the federal government, as it would be a violation of the federal government's sovereignty. The Court also held that the tax was not a valid exercise of the state's police power, as it was not necessary to protect the public health, safety, or welfare. The decision in The Wren case established the principle that states cannot tax the federal government, and it remains an important precedent in the area of federalism.

In The Wren, 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. Justice Field delivered the dissenting opinion and argued that it is unconstitutional for states to exercise jurisdiction over citizens of other states without their consent. He reasoned that if such power were allowed, then any state could pass laws regulating or restraining citizens from other states who are within its borders, thus infringing upon those individuals' rights under the Constitution's Privileges and Immunities Clause. Furthermore, he noted that allowing this type of extraterritorial authority would be contrary to public policy as it would lead to confusion and conflict between different jurisdictions. Ultimately, Justice Field concluded that while Congress has been given certain powers with respect to interstate commerce through Article I Section 8 of the Constitution, these do not include granting individual states authority over non-residents in matters involving private rights or disputes between two parties from different states.