House Intel Dem: Giuliani could be held in inherent contempt if he ignores subpoena | TheHill

"How the strategy moves forward - going forward on a criminal basis, a civil basis - you know I've heard people talk about bringing back inherent contempt. I think at this point the House would be willing to go forward with inherent contempt at least in terms of fining people."

"Your failure or refusal to comply with the subpoena, including at the direction or behest of the president or the White House, shall constitute evidence of obstruction of the House's impeachment inquiry and may be used as an adverse inference against you and the president," the chairmen warned in a letter to the president's personal attorney.