The House Judiciary Committee will contend Friday in court that it still needs information quickly from former Special Counsel Robert S. Mueller III’s investigation even though the House impeached President Donald Trump last month.

The federal appeals court in Washington set oral argument for Friday morning in two committee cases: a lawsuit to force former White House Counsel Don McGahn to testify about episodes from Mueller’s report on Russian interference in the 2016 election, and an application to see secret grand jury materials from that same investigation.

But after the Dec. 18 vote mainly along party lines to impeach Trump, the judges of the U.S. Court of Appeals for the District of Columbia Circuit had a new question: What does that congressional action mean for these court actions?

House attorneys responded in court filings that the information is critical for an upcoming impeachment trial in the Senate and possibly for more articles of impeachment against Trump.

[Judge backs House Judiciary in ruling on Mueller materials]

The House impeached Trump on two articles: abuse of power and obstruction of Congress.

McGahn’s testimony is relevant to ongoing committee investigations into Trump’s conduct and “whether to recommend additional articles of impeachment,” House lawyers wrote.

The committee says McGahn witnessed firsthand Trump’s actions to obstruct the Mueller investigation, including “firing FBI Director James Comey as well as directing McGahn to fire the Special Counsel and then lie about it.”

Testimony about that “would constitute powerful evidence of the pattern of obstructive behavior” described in the second article of impeachment, House lawyers wrote.

[Judge questions keeping Mueller grand jury materials from House]

McGahn’s testimony also could affect legislative proposals to govern interactions between the White House and the Justice Department when it comes to ongoing civil and criminal matters, the House lawyers state.

And the grand jury materials — first subpoenaed eight months ago — would be “critical” in a Senate impeachment trial.

That material “bears on the President’s solicitation of interference by Ukraine” in the 2020 presidential election, specifically a passage in the Mueller report regarding a false theory that Ukraine rather than Russia interfered in the 2016 election and a supposed “peace plan” for Ukraine promoted by Russian interests, the committee attorneys contend.

The Justice Department, in a court filing addressing the same questions, contends the impeachment vote should mean the McGahn case should be dismissed.

The article of impeachment on obstruction of Congress cites the McGahn case as an example of Trump’s actions to prevent testimony from current and former officials, DOJ argues in a filing.

That means that if the court resolved the McGahn case now, “it would appear to be weighing in on a contested issue in any impeachment trial,” the Justice Department wrote.

The DOJ added that means there is a “now very real possibility of this Court appearing to weigh in on an article of impeachment at a time when political tensions are at their highest levels—before, during, or after a Senate trial regarding the removal of a President.”

A federal district judge in November ordered McGahn to testify before the House Judiciary Committee on a subpoena. The Trump administration appealed.

Some House Democrats consider the McGahn case the key test of congressional subpoena power for other ongoing investigations.

And a federal district judge ordered the Justice Department to give the grand jury information to the committee. The Trump administration has appealed.