Blackmer v. United States, 284 U.S. 421 (1932), is a decision of the Supreme Court of the United States. Harry M. Blackmer was a United States citizen resident in Paris. Blackmer was found guilty of contempt by the Supreme Court of the District of Columbia for refusing to appear as a witness for the United States in a criminal trial, which is related to the Teapot Dome Scandal, after being subpoenaed. Blackmer was subsequently fined $30,000 and the costs of the court. Blackmer challenged the fine under the due process clause of the Fifth Amendment.