The Washington and the Gregory was a United States Supreme Court case that was decided in 1869. The case involved a dispute between two vessels, the Washington and the Gregory, over the right to navigate a particular stretch of the Mississippi River. The Washington was a steamboat owned by the United States government, while the Gregory was a privately owned vessel. The dispute arose when the Washington attempted to navigate the river, but was blocked by the Gregory. The Washington argued that it had the right to navigate the river, as it was a government vessel. The Gregory argued that it had the right to block the Washington, as it was a privately owned vessel. The Supreme Court ultimately sided with the Washington, ruling that the government vessel had the right to navigate the river. The Court held that the government had the right to use the river for navigation, and that the Gregory had no right to block the Washington. The Court also held that the government had the right to regulate navigation on the river, and that the Gregory had no right to interfere with the government's navigation. The decision in The Washington and the Gregory established the principle that the government has the right to regulate navigation on navigable waters, and that private vessels have no right to interfere with the government's navigation. This decision has been cited in numerous cases since, and is still an important precedent in the area of navigable waters.

In The Washington and the Gregory, a majority of the Supreme Court held that Congress had no authority to pass an act allowing for the seizure of vessels engaged in illegal slave trading. However, Justice Field dissented from this opinion. He argued that Congress did have such authority under its power to regulate foreign commerce as granted by Article I Section 8 of the Constitution. Furthermore, he maintained that it was within Congress' power to make laws necessary and proper for carrying into execution any other powers vested by the Constitution in any department or officer thereof. In his view, since slavery was prohibited by international law at this time, seizing vessels involved in illegal slave trading would be necessary and proper for executing Congressional powers related to foreign commerce regulation.