Cohens v. Virginia, 19 U.S. 264 (1821), is a landmark case by the Supreme Court of the United States that is most notable for the Court's assertion of its power to review state supreme court decisions in criminal law matters if defendants claim that their constitutional rights have been violated. The Court had previously asserted a similar jurisdiction over civil cases involving U.S. parties.

John Marshall was an American statesman, lawyer, and Founding Father who served as the fourth chief justice of the United States from 1801 until his death in 1835. He remains the longest-serving chief justice and fourth-longest serving justice in the history of the U.S. Supreme Court, and is widely regarded as one of the most influential justices ever to serve. Prior to joining the court, Marshall briefly served as both the U.S. secretary of state under President John Adams, and a representative, in the U.S. House of Representatives from Virginia, thereby making him one of the few Americans to serve on all three branches of the United States federal government.