The stakes couldn’t be higher. Trump’s ability to stave off a Senate conviction after last month’s House votes to impeach him is essential to his political survival. But court losses for the president in either or both cases argued Friday will help to keep the impeachment issue alive throughout 2020, while giving House Democrats their own boost in a consequential constitutional showdown with Trump’s Justice Department that ultimately appears headed to the Supreme Court.

“This is it,” Doug Letter, the lead House counsel, argued during the second half of Friday’s proceedings over the Mueller grand jury material. “There is nothing more important than determining whether the president of the United States should remain the president of the United States.”

Letter also argued that Trump shouldn’t rest easy just because the House has already voted to impeach the president over his efforts to pressure Ukraine leaders into investigating his political rivals. How the courts rule in the Democrats’ bid for more testimony and documents connected back to the Mueller probe into 2016 Russian election interference could still yield additional impeachment articles against Trump, he said.

“Yes, that is on the table. There’s no doubt,” Letter said, while also confirming to the judges that his remarks had sign off from House Speaker Nancy Pelosi.

The historical significance of Friday’s arguments was apparent in pretty much every exchange before the D.C. Circuit panels, which were composed of two Republican presidential appointees and one judge named by a Democrat. For example, a GOP-appointed judge assigned to both cases, George W. Bush nominee Thomas Griffith, pressed the Justice Department over whether Trump’s blanket refusal to cooperate with House impeachment probes was an unprecedented act of contempt for the legislative branch.

“Has there ever been an instance of such a broad-scale defiance of a congressional request for information in the history of the republic?” Griffith asked Hashim Mooppan, the Trump-appointed deputy assistant attorney general and former partner with McGahn at the law firm Jones Day.

Mooppan didn’t immediately offer a direct answer, but said there were “real dangers” in the court interjecting itself into the dispute.

Griffith brushed that aside. “What’s the answer to the question?” he pressed.

“I don’t want to fight with the premise to the question, but there is a lot of dispute about whether this is a wide-scale massive resistance,” Mooppan replied, adding that Trump’s view may be that Congress has never acted as illegitimately as it has in the current impeachment process.

"The court should not be refereeing who’s right or wrong about whether the president is acting totally unusually or Congress is acting totally unusually," Mooppan added.

The U.S. Court of Appeals for the District of Columbia. | Alex Wong/Getty Images

Some of the Justice Department’s arguments in the cases seemed potentially awkward for the Trump administration.

As Mooppan sought to emphasize the other avenues the House could use to penalize the president for non-compliance with subpoenas, the DOJ lawyer acknowledged that impeachment was one such lever. But Mooppan declined to say whether the House’s decision to impeach Trump over obstruction of Congress was justified.

“It’s not that there are no remedies. There are political remedies. … The House has the power to block appropriations, to block legislation,” Mooppan said, noting also that the Senate could weigh in by holding up confirmations.

After Griffith chimed in with a suggestion about impeachment, Mooppan mostly dodged.

“I’m not going to get into, on any particular fact pattern, whether [that] would be appropriate or not,” the DOJ attorney said.

But Griffith also pressed another one of the House’s attorneys, Megan Barbero, about whether those other remedies were in fact sufficient to resolve the dispute without the courts getting involved.

“Cut the appropriations. Get the Senate to stop confirming judges. Make it an article of impeachment. You're not without remedy here,” Griffith said.

“It is true that the House has other remedies available to it,” Barbero replied. “Those other remedies are not effective in obtaining a remedy for this specific injury of getting information in a timely fashion.”

Griffith questioned Barbero at length about what would happen if the court sided with the House and the president simply invoked executive privilege to block McGahn from answering questions.

“We would expect to reopen the accommodations process,” Barbero responded.

While decisions from the D.C. Circuit are possible by the end of the month, it’s still unclear whether they’ll arrive before the GOP-led Senate has rendered its verdict on whether Trump should be the first U.S. president to be booted from the White House.

But even a definitive ruling that McGahn must testify might not yield useful information for the House anytime soon. If the Justice Department’s arguments for absolute immunity for presidential advisers are rejected by the courts, litigation on a question-by-question basis is expected to follow.

That legal territory, which is even more uncharted than the threshold question of whether McGahn and similarly senior advisers can essentially ignore a subpoena, seemed to concern at least Griffith and fellow GOP appointee Karen Henderson.

“What happens next?” Griffith asked repeatedly during the 75-minute argument on the McGahn subpoena.

The session about the House’s request for grand jury secrets in the Mueller report and underlying records stretched even longer, to more than an hour and a half.

Much of that time was spent addressing numerous queries from Judge Neomi Rao, a Trump appointee, about whether U.S. District Court Chief Judge Beryl Howell had the authority back in October to order the Justice Department to turn over the grand jury material to the House Judiciary Committee.

Rao seemed to accept that Howell could release the court’s veil of secrecy over the records, but she also suggested that forcing the executive branch to fork them over to Congress raised thornier questions.

That prompted Letter, the House counsel, to repeatedly raise the specter of Congress returning to use of force to enforce its subpoenas — a practice not attempted for nearly a century. But as the House lawyer spoke of the potential for such confrontations leading to violence, it appeared he was highlighting the dangers of such an approach rather than seriously suggesting returning to the coercive methods employed until the 1930s.

“I guess what we would do is use the main remedy the House has had from the beginning, we’ll send the sergeant-at-arms over to the Justice Department. I cannot imagine anyone is going to interfere with him doing his duty as an officer of the House,” Letter said.

When pressed by Rao about what would happen if the Justice Department refused to comply, the House counsel added: “We can send the sergeant-at-arms and he can have a gun battle.”

Letter quickly said that it was “obvious” how such an effort could lead to chaos and why that practice was abandoned.

"Instead, we go to court,” said Letter, who in early 2018 ended a four-decade career as a senior Justice Department attorney.

Some of the heated exchanges on the subject seemed to have been triggered by Justice Department lawyer Mark Freeman’s statement to Rao earlier in the hearing that he’d have to ask his superiors what they would do if they were authorized, but not required, to turn over the grand jury secrets to Congress. Freeman added later that “as a career, line attorney” it wasn’t for him to predict what Attorney General William Barr would do.

However, Freeman did suggest that House lawyers were being cagey about whether additional impeachment articles against Trump were only theoretically possible or actually the subject of serious discussion by House leaders or the House Judiciary Committee.

“There’s a very carefully scripted language," the DOJ lawyer said.

Judge Judith Rogers, a Clinton appointee, took a dim view of those arguments. “This is the counsel representing the committee on behalf of the House. This is not some casual remark,” Rogers said.

Although further action is expected soon on the House-passed articles, the Senate impeachment trial schedule remains a work in progress, with Majority Leader Mitch McConnell and Pelosi still in a standoff over how to proceed on the two House-passed articles against Trump from December tied to allegations that the president withheld military aide from Ukraine until it agreed to investigate his Democratic rivals.

House Democrats are nonetheless antsy for quick decisions. They’ve already won both fights before federal district court judges in Washington, and House lawyers urged the appellate panels hearing Friday’s arguments to reject the Trump-led Justice Department’s bids to have those earlier rulings tossed out.

In court briefs filed late last month, the Democrats pleaded for the chance to uncover incriminating material against Trump that could strengthen their hand during a Senate impeachment trial.

They’ve homed in on McGahn, who spent 30 hours meeting with Mueller’s team, and who they want to question under oath about what he witnessed in the White House as the special counsel probe bore in on the president’s behavior.

Convincing the judges that McGahn’s testimony or details from the unredacted Mueller report are critical to the impeachment articles will require some finesse since the pending charges against Trump focus on his dealings with Ukraine this past spring, half a year after McGahn quit his post and as Mueller’s probe was winding down.

Still, House lawyers argue that the testimony and records they’re demanding could buttress the impeachment drive by confirming Trump’s tendency to try to thwart investigators.

A win for the House could cause Trump headaches beyond the current impeachment showdown. The Democrats have said they haven’t foreclosed their option of passing additional articles to remove Trump if the judges were to order the release of evidence showcasing additional presidential crimes.

DOJ has multiple lines of legal defense against the House Democrats. In the McGahn case, it has argued that the former White House counsel, like many other government officials who served under Trump, enjoy “absolute immunity” from speaking to congressional investigators. Additionally, DOJ warned the court that it would be opening up a sack of hot potatoes by taking sides in a dispute between the other two branches of government.

“If this court rules on the merits one way or the other, you can be assured that the opinion this court issues will be waved on the floor of the Senate by one side or the other as evidence that the president is guilty or the president is innocent,” Mooppan said Friday.

Rulings from the two D.C. Circuit court panels are unlikely to amount to the final say in the cases. The losers in either or both cases could ask the appeals court’s full, active bench — consisting of seven Democratic-appointed judges and four Republican appointees — to weigh in. That could lead to rulings that favor the Democratic-led House Judiciary Committee.

DOJ has signaled it would go to the Supreme Court if it loses. Escalating either or both fights would set the stage for more possible precedent-shattering decisions on presidential power and Capitol Hill oversight. The justices have already agreed to hear arguments in March involving congressional and local criminal prosecutors’ subpoenas for Trump’s tax and financial records.

Friday’s D.C. Circuit arguments took place in the court’s regular fifth-floor courtroom. Four judges in all were involved. The McGahn case went first and featured Rogers working alongside Griffith and Henderson. After a 15-minute break, the court reconvened for the Mueller grand jury case, with Rogers and Griffith joined by Rao.

If the cases divide the three-judge panels hearing them, Griffith could turn out to be a swing vote.

After Trump lost a court challenge at the D.C. Circuit last October to a broad-ranging House subpoena for his financial records, the full bench of the court divided as it declined to rehear the case en banc. The only judge who appeared to cross ideological lines was Griffith, who declined to join three Republican-appointed dissenters who said the full court should consider Trump’s arguments that the House subpoena went too far.

The central, dissenting opinion backing Trump in the financial-records case was written by Rao.