Congressional Powers of Investigation
One of the most important nonlegislative functions of the Congress is the power to investigate. This power is usually delegated to committees -- either the standing committees, special committees set up for a specific purpose, or joint committees composed of members of both houses. Investigations are conducted to gather information on the need for future legislation, to test the effectiveness of laws already passed, to inquire into the qualifications and performance of members and officials of the other branches, and on rare occasions, to lay the groundwork for impeachment proceedings. Frequently, committees call on outside experts to assist in conducting investigative hearings and to make detailed studies of issues.
There are important corollaries to the investigative power. One is the power to publicize investigations and their results. Most committee hearings are open to the public and are widely reported in the mass media. Congressional investigations thus represent one important tool available to lawmakers to inform the citizenry and arouse public interest in national issues. Congressional committees also have the power to compel testimony from unwilling witnesses, and to cite for contempt of Congress witnesses who refuse to testify and for perjury those who give false testimony.