You've undoubtedly been hearing a lot about contempt of Congress in recent weeks. During the past week there's been increasing talk among Dems about resorting to what's known as "inherent contempt" of Congress, whereby Congress would arrest supposed contemnors, put them on trial, find them guilty, and then imprison or fine them--or both. What's this about?
Here's the Wikipedia version:
Under this process, the procedure for holding a person in contempt involves only the chamber concerned. Following a contempt citation, the person cited is arrested by the Sergeant-at-Arms for the House or Senate, brought to the floor of the chamber, held to answer charges by the presiding officer, and then subjected to punishment as the chamber may dictate (usually imprisonment for punishment, imprisonment for coersion, or release from the contempt citation).
Concerned with the time-consuming nature of a contempt proceeding and the inability to extend punishment further than the session of the Congress concerned (under Supreme Court rulings), Congress created a statutory process in 1857. While Congress retains its "inherent contempt" authority and may exercise it at any time, this inherent contempt process was last used by the Senate in 1934, in a Senate investigation of airlines and the U.S. Postmaster. After a one-week trial on the Senate floor (presided over by Vice President John Nance Garner, in his capacity as Senate President), William P. MacCracken, Jr., a lawyer and former Assistant Secretary of Commerce for Aeronautics who was charged with allowing clients to remove or rip up subpoenaed documents, was found guilty and sentenced to 10 days imprisonment.
MacCracken filed a petition of habeas corpus in federal courts to overturn his arrest, but after litigation, the U.S. Supreme Court ruled that Congress had acted constitutionally, and denied the petition in the case Jurney v. MacCracken.
Presidential pardons appear not to apply to a civil contempt procedure such as the above, since it is not an "offense against the United States" or against "the dignity of public authority."
The reason for resorting to "inherent contempt" rather than the statutory process that has been in place since 1857 is obvious: in the statutory process the matter would be referred to AG Bill Barr. You may have also noticed that the Dems are talking about using "inherent contempt" to levy heavy fines. This is, presumably, to avoid a petition of habeas corpus. My guess is that even as we read this there are smart lawyers in the administration who are working on challenges to this attempt to avoid judicial review on constitutional grounds. I'm also guessing that the courts would find a way to review such a high handed and potentially abusive procedure.
If you really want to get into the weeds on this, I found a Congressional Research Service report yesterday: Congress’s Contempt Power and the Enforcement of Congressional Subpoenas: Law, History, Practice, and Procedure (Updated May 12, 2017). It's long, but the section on Inherent Contempt is covered in only about six pages.
The key to all of this is that Congress's power of inherent contempt can only be exercised in matters over which Congress has jurisdiction. In other words, Congress must be exercising a valid legislative or oversight function, not attempting to misuse its powers for a purely political purpose--such as, to embarrass the president. That is the ground on which this will be fought if Congress attempts to use inherent contempt.