Throughout history congress has engaged in oversight of the executive branch -- the review, monitoring and supervision of the implementation of public policy. The first several Congresses inaugurated important oversight techniques as special investigations, reporting requirements, resolutions of inquiry, and use of the appropriations process to review executive activity. Contemporary developments, moreover, have increased the legislature's capacity and capabilities to check on and check the Executive. Public laws and congressional rules have measurably enhanced Congress's implied power under the Constitution to conduct oversight. Despite its lengthy heritage, oversight was not given explicit recognition in public law until enactment of the Legislative Reorganisation Act of 1946. That act required House and a Senate standing committees to exercise 'continuous watchfulness' over programs and agencies within their jurisdiction. Since the late 1960s Congress has shown increasing interest in oversight for several major reasons. These include the expansion in number and complexity of federal programs and agencies; increase in expenditures and personnel, including contract employees; rise (until recently) in the budget deficit; and the frequency divided government, with Congress and the White House controlled by different parties. Major partisan disagreements over priorities and processes also heighten conflict between the legislature and the executive. Oversight occurs in virtually any congressional activity and through a wide variety of channels, organisations, and structures. These range from formal committee hearings to informal Member contracts with executive officials, from staff studies to support agency reviews, and from casework conducted by Member offices to studies prepared by non-congressional entities, such as statutory commissions and offices of inspector general.