United States v. Cook is a United States Supreme Court case that was decided in 1873. The case involved a dispute between the United States and William Cook, a citizen of the United States. Cook had been convicted of violating the Revenue Act of 1864, which prohibited the sale of distilled spirits without a license. Cook argued that the Act was unconstitutional because it violated the Fifth Amendment's protection against double jeopardy. The Supreme Court held that the Revenue Act of 1864 was constitutional and that Cook's conviction was valid. The Court reasoned that the Act was a valid exercise of Congress' power to tax and regulate commerce, and that the Fifth Amendment did not apply because the Act did not impose a criminal penalty. The Court also held that the Act did not violate the Due Process Clause of the Fifth Amendment because it provided adequate notice of the prohibited conduct and did not impose an excessive penalty. In conclusion, the Supreme Court held that the Revenue Act of 1864 was constitutional and that Cook's conviction was valid. The Court reasoned that the Act was a valid exercise of Congress' power to tax and regulate commerce, and that the Fifth Amendment did not apply because the Act did not impose a criminal penalty. The Court also held that the Act did not violate the Due Process Clause of the Fifth Amendment because it provided adequate notice of the prohibited conduct and did not impose an excessive penalty.

In United States v. Cook, the Supreme Court was asked to determine whether a defendant could be convicted of murder in Indian Territory when he had killed another person while defending himself against an attack. The majority opinion held that the defendant could not be convicted because there was no law prohibiting self-defense in Indian Territory at the time of his actions. Justice Field dissented from this decision and argued that Congress had enacted laws which prohibited killing without justification or excuse, regardless of where it occurred within U.S. jurisdiction, and thus should apply to all persons living under its authority - including those residing in Indian Territory at the time of this case. He further noted that even if such laws did not exist prior to 1871 (when they were first enacted), then common law principles would still have applied as part of customary international law; therefore, any act committed by a citizen on foreign soil must conform with both domestic and international standards for criminal behavior unless otherwise specified by treaty or other agreement between nations involved in said action(s).