WASHINGTON (CN) — In a hearing that will determine whether a onetime top adviser to President Donald Trump will testify before Congress, the D.C. Circuit sought confirmation Friday on whether House Democrats plan to file more articles of impeachment.

The House Judiciary Committee brought the lawsuit in August, weeks before the impeachment took shape, seeking to compel testimony from former White House counsel Don McGahn. Though the White House barred McGahn from complying with a congressional subpoena, he spent months in 2018 cooperating extensively with the investigation by then-Special Counsel Robert Mueller of Russian interference in Trump’s election.

McGahn resigned that October, returning to private practice at the firm Jones Day, but is seen as a crucial witness to evidence that Trump tried to obstruct Mueller’s probe. Setting the stage for this morning’s appeal, U.S. District Judge Ketanji Brown ordered McGahn in November to testify.

U.S. Circuit Judge Thomas Griffith pressed House attorney Megan Barbero at the hearing to explain the relevance of McGahn’s testimony, given that the House impeached Trump last month for abuse of power and obstruction of Congress in the Ukraine investigation.

“So you’re saying there may be new articles of impeachment coming?” asked Griffith.

Barbero parried the question, emphasizing that the House was in court to protect legislative oversight authority as well as to obtain testimony relevant to its ongoing impeachment investigation.

“We are in a situation now where there is unprecedented refusal to comply with a congressional subpoena,” Barbero said.

With the House attorney noting that the court has in the past resolved legal questions surrounding subpoena enforcement, Griffith pushed back.

“This isn’t a garden-variety subpoena enforcement,” the Bush-appointed judge said. “It is a dispute between two different branches of government.”

Griffith also directed tough questions Friday at Justice Department attorney Hashim Mooppan, who argued that senior-level White House aides are shielded by absolute testimonial immunity.

“Has there ever been an instance of such broad-scale defiance of a congressional request for information in the history of the republic?” Griffith asked.

“Has that ever happened before?” the judge asked again, before answering his own question. “No, it hasn’t,” he said.

But Mooppan pushed back arguing the judges should not be refereeing the political dispute.

“If this court rules on the matter one way or the other, you can be sure that it will be waived by one party or the other on the floor of the Senate to prove that the president is innocent or that he is guilty,” the Justice Department attorney said.

But the appellate panel — rounded out by U.S. Circuit Judges Karen Henderson and Judith Rogers — collectively took issue with the argument that the judicial branch has no role to play.

Rogers, a Clinton appointee, said the government was arguing for absolute rule by the executive branch.

Holding firm to the claim that the House lacks standing, Mooppan argued that an appropriate “give and take in the political process” allows for Democrats to pass a statute to enforce the subpoena.

“It takes two,” Rogers clapped back, drawing laughter from the packed courtroom. “We’re at the point now where there is no cooperation,” the judge later added.

Agreeing, Mooppan said the judicial branch should stay out of the “political food fight.”

Shutting down the argument, Griffith said the Supreme Court makes clear the courts can step in to resolve clashes between branches. “It may be a limited role but there is a role,” he said.

But Griffith also questioned repeatedly why the House did not choose an alternate route to taking the McGahn subpoena straight to the courts, adding they could have blocked judicial nominees or congressional appropriations. “Make it an article of impeachment,” the judge added, “you are not without amenity here.”

The D.C. Circuit heard the case destined to reach the Supreme Court along with the Justice Department appeal of a ruling that allows the House to access special grand jury material from the Mueller investigation.

Both carry heavy implications for the upcoming Senate trial with Democrats planning to use any evidence obtained in the legal battles to prove Trump should be removed from office. Griffith and Rogers heard the second oral arguments along with U.S. Circuit Judge Neomi Rao, a Trump appointee.

Henderson is an appointee of President George H.W. Bush, while Griffith was appointed by President George W. Bush.