Three House committees conducting depositions set deadlines for subpoenas seeking documents from Trump lawyer Rudy Giuliani, the Pentagon, and the Office of Management and Budget. Giuliani refused to comply, as did the others.

At the same time, investigators are seeking documents from Vice President Mike Pence and others – with the implied threat that court action could follow. Pence, too, has refused to comply. Thus far, the House has not asked courts to enforce the subpoenas.

“That is the most likely type of issue that could go before the Supreme Court,” says George Washington University Law School professor Jonathan Turley, lead counsel in the last Senate impeachment trial of a federal judge in 2010. The White House, he says, “did untold damage to (Trump’s) primary defense” of executive privilege by instead focusing on claims of partisanship.