United States v. Parker is a United States Supreme Court case that dealt with the issue of whether the federal government had the authority to regulate the sale of alcohol in Indian country. The case was brought by the United States against William Parker, a member of the Choctaw Nation, who was accused of selling alcohol to members of the Choctaw Nation in Indian country without a license. The Supreme Court held that the federal government had the authority to regulate the sale of alcohol in Indian country. The Court reasoned that the federal government had the power to regulate the sale of alcohol in Indian country because it had the power to regulate commerce with Indian tribes. The Court also held that the federal government had the power to regulate the sale of alcohol in Indian country because it had the power to protect the health and welfare of the Indians. The Court's decision in United States v. Parker established that the federal government had the authority to regulate the sale of alcohol in Indian country. This decision has been cited in numerous cases since then, and it has been used to support the federal government's authority to regulate the sale of alcohol in Indian country.

Justice Field wrote the dissenting opinion in United States v. Parker, arguing that Congress did not have the authority to pass a law prohibiting citizens from selling liquor on Indian reservations. He argued that while Congress had the power to regulate commerce with Native American tribes, it could not prohibit such activities altogether without infringing upon their sovereignty and rights as independent nations. Furthermore, he noted that this was an issue of state rather than federal jurisdiction since states were responsible for regulating alcohol sales within their borders. He concluded by stating that if Congress wanted to prevent Indians from engaging in certain activities related to alcohol sales then they should do so through treaties or other agreements between them and individual tribes instead of passing laws which applied across all tribal lands indiscriminately.