"Congressional oversight of policy implementation and administration has occurred throughout the history of the United States government under the Constitution. Oversight--the review, monitoring, and supervision of operations and activities--takes a variety of forms and utilizes various techniques. These range from specialized investigations by select committees to annual appropriations hearings, and from informal communications between Members or congressional staff and executive personnel to the use of extra-congressional mechanisms, such as offices of inspector general and study commissions. Oversight, moreover, is supported by a variety of authorities--the Constitution, public law, and chamber and committee rules--and is an integral part of the system of checks and balances between the legislative and executive branches. This report will be updated as events require."
CRS Report for Congress, 97-936