Congressional power to conduct inquiries and to exercise oversight respecting the Executive Branch is broad and well-established. This power is not unlimited, however. Its use must be confined to inquiries concerning the administration of existing laws or the determination of whether new or additional laws are needed.
Congress may not conduct investigative or oversight inquiries for the purpose of managing Executive Branch agencies or for directing the manner in which the Executive Branch interprets and executes the laws.
The Supreme Court’s decisions in Buckley v. Valeo, 424 U.S. 1 (1976) (per curiam), and INS v. Chadha, 462 U.S. 919 (1983), establish an area of executive authority in the interpretation and implementation of statutes. Congress may not take action, including action in furtherance of its inquiry and oversight powers, that interferes with that executive authority, except through the enactment of legislation in full compliance with constitutional requirements.