This case stems from a Senate investigation into allegations of misconduct in the Department of Justice.   As part of the investigation, a Senate special commit" subpoenaed Mally S. Daugherty, a bank president and brother of Attorney General Harry M Daugherty who had resigned as the investigation was beginning The witness failed to appear and was held in contempt of Congress. Daugherty sought relief on a writ of habeas corpus, challenging the authority of the Senate to compel his testimony.

Mr. Justice Van Devanter delivered the opinion of the court

The first of the principle questions, the one the Witness particularly presses on our attention, is ... whether the Senate - or the House of Representatives, both being on the same plane in this regard-has power, through its own process, compel a private individual to appear before it or one of its committees and give testimony needed to enable it efficiently to exercise a legislative function belonging to it under the Constitution.

The Constitution provides for a Congress, consisting of a Senate and House of Representatives, invests it with "all legislative powers" granted to United States, and with power "to make all I which shall be necessary and proper" for carrying into execution these powers and "all other powers vested by the Constitution in the United States or in any department or officer thereof. ... Other provisions show that, while bills can become laws only after being considered and passed by both houses of Congress, each house is to be distinct from the other, to have its own officers and rules, and to exercise its legislative function independently ... But there is no provision expressly investing either house with power to make investigations and exact testimony, to the end that it may exercise its legislative function advisedly and effectively. So the question arises whether this power is so far incidental to the legislative function as to be implied.

In actual legislative practice, power to secure needed information by such means has long been treated as an attribute of the power to legislate. It was so regarded in the British Parliament and in the colonial Legislatures before the American Revolution, and a like view has prevailed and been carried into effect in both houses of Congress and in most of the state Legislatures.

This power was both asserted and exerted by the House of Representatives in 1792, when it appointed a select committee to inquire into the [Gen. Arthur] St. Clair expedition and authorized the committee to send for necessary persons, papers and records. Mr. Madison, who had taken an important part in framing the Constitution only five years before, and four of his associates in that work, were members of the House of Representatives at the time, and all voted for the inquiry... [T]he Senate ... inquiry ordered in 1859 respecting the raid by John Brown and his adherents on the armory and arsenal of the United States at Harper's Ferry is of special significance. The resolution directing the inquiry authorized the committee to send for persons and papers, to inquire into the facts pertaining to the raid and the means by which it was organized and supported, and to report what legislation, if any, was necessary to preserve the peace of the country and protect the public property. The resolution was briefly discussed and adopted without opposition….

The state courts quite generally have held that the power to legislate carries with it by necessary implication ample authority to obtain information needed in the rightful exercise of that power, and to employ compulsory process for the purpose....

We have referred to the practice of the two houses of Congress, and we now shall notice some significant congressional enactments.... They show very plainly that Congress intended thereby (a) to recognize the power of either house to institute inquiries and evidence touching subjects within its jurisdiction on which it was disposed to act, (b) to recognize such inquiries may be conducted through committees; (c) to subject defaulting and contumacious to indictment and punishment in the courts and thereby to enable either house to exert the power of inquiry "more effectually"; and (d) to open the way for obtaining evidence in such an inquiry, which otherwise could not be obtained, by exempting witnesses required to give evidence therein from criminal and penal prosecutions in respect of matters disclosed by their evidence....

... [I]n Kilbourn v. Thompson *** (1880)… [t]he question there was whether the House of Representatives had exceeded its power in directing one of its committees to make a particular investigation. The decision was that it had. The principles announced and applied in the case are-that neither house of Congress possesses a "general power of making inquiry into the private affairs of the citizen"; that the power actually possessed is limited to inquiries relating to matters of which the particular house "has jurisdiction" and in respect of which it rightfully may take other action; that if the inquiry relates to "a matter wherein relief or redress could be had only by a judicial proceeding" it is not within the range of power, but must be left to the courts, conformably to the constitutional separation of governmental powers; and that for the purpose of determining the essential character of the inquiry recourse may be had to the resolution or order under which it is made….

... [In] In re Chapman *** (1896) . .. [t]he inquiry there in question was conducted under a resolution of the Senate and related to charges, published in the press, that Senators were yielding to corrupt influences in considering a tariff bill then before the Senate and were speculating in stocks the value of which would be affected by pending amendments bill. Chapman appeared before the committee in response to a subpoena, but refused to answer questions pertinent to the inquiry, and was indicted and convicted under the act of 1857 for his refusal. The court sustained the constitutional validity of the act of 1857, and, after referring to the constitutional vision empowering either house to punish its members for disorderly behavior and by a vote of two- thirds to expel a member, held that the inquiry related to the integrity and fidelity of Senators in the discharge of their duties, and therefore to a matter "within the range of the constitutional powers of the Senate" and in respect of which it could compel witnesses to appear and testify...

The latest case is Marshall v. Gordon *** (1916). The question there was whether the House of Representatives exceeded its power in punishing, as for a contempt of its authority, a person — not a member — who had written, published, and sent to the chairman of one of its committees an ill-tempered and irritating letter respecting the action and purposes of the committee. Power to make inquiries and obtain evidence by compulsory process was not involved. The court recognized distinctly that the House of Representatives has implied power to punish a person not a member for contempt, as was ruled in Anderson v Dunn, supra, but held that its action in this instance was without constitutional justification.

While these cases are not decisive of the question we are considering, they definitely settle two propositions which we recognize as entirely sound and having a bearing on its solution: One, that the two houses of Congress, in their separate relations, possess, not only such powers as are expressly granted to them by the Constitution, but such auxiliary powers as are necessary and appropriate to make the express powers effective; and the other, that neither house is invested with "general" power to inquire into private affairs and compel disclosures, but only with such limited power of inquiry as is shown to exist when the rule of constitutional interpretation just stated is rightly applied....

We are of opinion that the power of inquiry — with process to enforce it — is an essential and appropriate auxiliary to the legislative function. It was so regarded and employed in American legislatures before the Constitution was framed and ratified. Both houses of Congress took this view of it early in their history...

We come now to the question whether it sufficiently appears that the purpose for which the witness's testimony was sought was to obtain information in aid of the legislative function. The court below answered the question in the negative and put its decision largely on this ground....

We are of opinion that the court's ruling on this question was wrong, and that it sufficiently appears, when the proceedings are rightly interpreted the object of the investigation and of the e secure the witness's testimony was to obtain information for legislative purposes.

It is quite true that the resolution directing the investigation does not in terms avow that it is intended to be in aid of legislation; but it does show the subject to be investigated was the administration of the Department of Justice — whether its functions were being properly discharged or were being neglected or misdirected, and particularly whether the Attorney General and his assistants were performing or neglecting their duties in respect of the institution and prosecution of proceedings to punish crimes and enforce appropriate remedies against the wrong doers; specific instances of alleged neglect being cited. Plainly the Subject was one on which legislation could be had and would be materially aided by the information which the investigation was calculated to elicit. This becomes manifest when it is reflected that the functions of the Department of Justice, the powers and duties of the Attorney General, and the duties of his assistants are all subject to regulation by congressional legislation, and that the department is maintained and its activities are carried on under appropriations as in the judgment of Congress needed from year to year.

The only legitimate object the Senate could have in ordering the investigation was to aid it in legislating, and we think the subject-matter was such that the presumption should be indulged that this was the real object. An express avowal of the object would have been better, but in view of the particular subject-matter was not indispensable....

We conclude that the investigation was ordered for a legitimate object; that the witness wrongfully refused to appear and testify before the committee was lawfully attached; that the Senate is entitled to have him give testimony pertinent to the inquiry, either at its bar or before the committee; and the district court erred in discharging him from custody under the attachment....

What has been said requires that the final order in the district court discharging the witness from custody be reversed.

Mr. Justice Stone did not participate in the consideration or decision of the case.