The Grapeshot was a Supreme Court case that dealt with the issue of whether a state could tax a federal instrumentality. The case arose when the state of Louisiana attempted to impose a tax on the Grapeshot, a steamboat owned by the United States government. The Grapeshot was used to transport troops and supplies for the Union Army during the Civil War. The Supreme Court held that the state of Louisiana could not impose a tax on the Grapeshot because it was a federal instrumentality. The Court reasoned that the federal government had exclusive authority over its own instrumentalities, and that the state could not interfere with the federal government's operations. The Court also held that the state could not impose a tax on the Grapeshot because it was engaged in a federal purpose. The Grapeshot case is an important precedent in the area of federalism. It established that the federal government has exclusive authority over its own instrumentalities, and that the states cannot interfere with the federal government's operations. The case also established that the states cannot impose taxes on federal instrumentalities that are engaged in a federal purpose.

In The Grapeshot, the Supreme Court was asked to decide whether a vessel that had been seized by the United States Navy for violating neutrality laws could be sold without first obtaining a court order. In an 8-1 decision, the Court held that no such court order was necessary and that Congress had given sufficient authority to the President of the United States to make such seizures and sales. Justice Field dissented from this opinion on two grounds: first, he argued that it violated due process because there was no opportunity for judicial review; second, he argued that Congress did not have constitutional authority to delegate its power over seizures and forfeitures in this manner. He concluded his dissent with a warning about how dangerous it would be if executive powers were allowed to expand unchecked in this way.