Congressional subpoena

A congressional subpoena is an order issued by a House or Senate committee requiring a person or organization to appear, testify or turn over records. Although the Constitution does not mention it, the Supreme Court has said that the power to investigate is an essential part of the legislative power, in cases such as McGrain v. Daugherty (1927).

Committee rules set who can issue one; chairs may issue them unilaterally in many committees, or a vote may be required. To be valid, the subpoena must relate to a legitimate legislative purpose, not merely to expose private affairs. Recipients may object on grounds such as executive privilege, attorney-client privilege or the Fifth Amendment right against self-incrimination.

When people ignore a subpoena, Congress has three options: criminal referral for Contempt of Congress, civil lawsuits to enforce it, or, in theory, inherent contempt. Disputes between Congress and the executive branch usually end in negotiation, since courts are slow. Subpoenas became prominent in investigations of the White House, the Justice Department and outside groups. Members of each party defend subpoenas when investigating the other party's administration and attack them when they are the target. They are also used alongside the grand jury subpoena, which is a separate tool.