The Camanche was a Supreme Court case that dealt with the issue of whether a state could tax a vessel owned by the United States. The case arose when the state of California attempted to impose a tax on the steamship Camanche, which was owned by the United States. The United States argued that the tax was unconstitutional because it violated the Supremacy Clause of the Constitution, which states that federal laws are supreme over state laws. The Supreme Court agreed with the United States and held that the tax was unconstitutional. The Court reasoned that the tax was a direct burden on the United States and thus violated the Supremacy Clause. The Court also held that the tax was a form of discrimination against the United States, as it was not imposed on other vessels owned by private citizens. The Court's decision in The Camanche established the principle that states cannot tax vessels owned by the United States. This principle has been applied in subsequent cases, and it remains an important part of the law today.

In The Camanche, the Supreme Court was asked to decide whether a steamboat named the Camanche had been lawfully seized by customs officers. In an 8-1 decision, Justice Field delivered the opinion of the court that affirmed the lower court's ruling and held that there was no legal basis for seizing or detaining the vessel. However, in his dissenting opinion Justice Swayne argued that under existing law it was within Congress' power to authorize such seizures when necessary for revenue purposes. He further noted that even if this particular seizure were not authorized by statute, it should be upheld as a valid exercise of executive authority since it served important public interests related to protecting government revenues from smuggling activities. Ultimately, he concluded that "the act complained of is one which has its foundation in necessity and reason."