A Supreme Court decision in 1927, Mcgrain v. Daugherty, settled the question of the right of Congress to conduct investigations when it stated: “the power of [congressional] inquiry - with the process to enforce it - is an essential and appropriate auxiliary to the legislative function.” The Court ruled that Congress could issue subpoenas, compel witnesses to testify, and hold them in contempt of Congress if they declined.

As a function of its legislative role under the Constitution, Congress can compel appearances and information from private persons and organizations and executive branch officials and agencies. The authority is absolute and Congress does not need to explain nor to justify its choice of subjects for hearings and investigations. In Watkins v. United States (1957) the Supreme Court stated: “The power of the Congress to conduct investigations is inherent in the legislative process. The power is broad. It encompasses inquiries concerning the administration of existing law as well as proposed or possibly needed statutes. . . . It comprehends probes into departments of the Federal Government to expose corruption, inefficiency, or waste.”

While the Constitution does not expressly state an investigative power for Congress, all aspects of oversight over the executive branch and investigation flow from the legislative role granted Congress in Article I. Oversight and investigation are tools to help Congress analyze the need for new legislation, to improve existing law, and to monitor the implementation of law by the executive branch. The constitutional doctrine of separation of powers and the checks and balances system further underlie the arguments for Congress exercising oversight over the executive branch.

Congress also plays a role in disclosing to the public how the government is performing and to create a historical record of official actions. For example, on the question of President Clinton’s pardons, there is no official forum outside of the congressional hearing process where facts and evidence can inform the public, and witnesses can speak in their own words. Without congressional hearings, the only record would be newspaper and media stories which have no official standing and carry no guarantee of completeness nor accuracy.

However, the Supreme Court has cautioned Congress in its use of this absolute power to investigate. In the Watkins case it said: “No inquiry is an end in itself, it must be related to, and in furtherance of, a legitimate task of the Congress.” Other restrictions on the power include the fact that witnesses before congressional committees retain the right to plead the Fifth Amendment of the Constitution against self-incrimination. The Constitution also grants the President implied authority to claim “executive privilege” as a protection against revealing the content of conversations and papers he considers to be confidential. The Supreme Court has not yet definitively settled the parameters within which executive privilege can be claimed, but its use has often thwarted investigations.

As for enforcement, if witnesses do not comply with a congressional subpoena, they could be held in contempt of Congress. Congress may choose to refer such cases to the Justice Department for prosecution. Current law treats contempt of Congress as a misdemeanor and allows for imprisonment of up to one year and a $1,000 fine. Further criminal prosecution is also possible, but this is left to the discretion of the U.S. Attorney, who may impanel a grand jury to issue an indictment. Finally, if a witness knowingly gives false information to a congressional committee, he/she may be cited for perjury and be subject to prosecution.