This power has not been used in decades, but it does exist. It process allows the Congress to send its Sergeant at Arms to arrest and incarcerate the scofflaw after a hearing until there is compliance. This inherent power was largely used before criminal contempt statutes came into existence (1857). The Supreme Court has repeatedly held that this power is implied by the constitutional authority of Congress to legislate, and the institution's power of self-preservation. The seminal case of McGrain v. Daugherty arose from a Senate investigation into the alleged failure of the Attorney General to prosecute federal antitrust violations associated with the Teapot Dome Scandal.
The Court has outlined the limits of that authority in later cases, saying no act is punishable for contempt “unless it is of a nature to obstruct the performance of the duties of the legislature” thus connecting it directly to the power to legislate, not law enforcement, which is the duty of the executive and judiciary. MacCracken. The court found in MacCracken that the House had no inherent contempt authority when it attempted to investigate a private bankruptcy in which the US was a creditor, that was a judicial, not legislative matter in the Court's opinion. Bannon was involved in an attempt to obstruct legislators in the performance of their official duties, i.e., counting electoral votes. He contemptuously refused to cooperate and thereby obstruct the investigation of this grave matter by a duly constituted committee of the House. Clearly the House's contempt citation is within the delineated limits of implied or inherent contempt. The power to hold a congressional witness in contempt has not been used since the 1930's, but has been referred to since in an effort to obtain compliance. Sam Irving, chairman of the Select Committee investigating Watergate, invoked the inherent contempt power several times to encourage compliance with that committee’s requests for information during its investigation of the Nixon Administration's campaign activities.The latest subpoenas have been issued to members of Trump's inner White House staff: Stephen Miller, former senior advisor; Keith Kellogg, former national security advisor to Mike Pence; Johnny McEntee, former personnel director and others including Nicholas Luna, a bodyguard who was in the Oval when Trump pressured Pence to refuse to certify the election. Miller has already made public statements that he will not comply with his subpoena. Participants in the coup conspiracy led by Trump, will continue to use litigation as a delaying tactic until the expiration of the current Congress. Winning cases is irrelevant; Trump lost his latest effort to block release of documents on grounds of executive privilege from the National Archives. Mark Meadows also expressed his unwillingness to cooperate until the Supreme Court rules on Trump's bogus executive priviege claims. If Bannon is not indicted, witnesses will have every motivation to consider compliance optional.
Since Garland, who is a conservative, continues to hide under a rock or IRS v, Chadha, take your pick, the Select Committee must use every power it possesses to obtain relevant evidence to preserve the Republic and itself. That evidence will reveal the malignant actor behind the mindless minions who attacked the seat of government to disrupt the Electoral College vote count. We are here because of the antiquated Electoral College system that the conspirators intended to game. ("Send in the Kraken!") A legitimate legislative purpose could be the replacement of this obsolete, vulnerable system with a national popular vote. States would be responsible for certifying their vote count and Congress would be reduced to a merely ministerial role of announcing the result.