A subpoena (pronounced 'suh-pee-nuh') is a writ commanding a person to appear under penalty (from Latin).
It is used to compel the testimony of witnesses in a trial. Subpoenas are issued by the clerk of the court in the name of the judge presiding over the case in which the witness is to testify. Typically subpoenas are issued "in blank" and it is the responsibility of the lawyer representing the plaintiff or defendant on whose behalf the testimony is to be given to serve the subpoena on the witness.
Issuance of subpoenas for proceedings in the United States district courts is governed by Rule 45 of the Federal Rules of Civil Procedure. Many state courts in the US have adopted Rule 45 or similar procedures.
The United States Congress also has the power to issue subpoenas and can punish individuals who fail to comply by contempt of Congress, which is similar to contempt of court.
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