House Democrats asked a federal appeals court in Washington on Friday to reconsider enforcing a congressional subpoena for President Trump’s former White House counsel Donald McGahn.

The request comes after a divided panel of the U.S. Court of Appeals for the D.C. Circuit found that the courts have no authority to resolve the separation-of-powers dispute between the White House and Democrats in Congress.

Lawyers for House Speaker Nancy Pelosi (D-Calif.) want a full complement of judges on the appeals court to overturn the ruling from a three-judge panel of the same court. If last week’s ruling stands, it means McGahn can defy the subpoena from the House Judiciary Committee.

Even if the full D.C. Circuit agrees to take a second look, the case is likely to be appealed to the Supreme Court.

“The stakes of the Committee’s inquiry are exceedingly high,” the House argued in a 17-page appeal. “The Committee is investigating allegations of President Trump’s improper political influence into ongoing criminal matters. McGahn was a key eyewitness to these events whom President Trump tried to enlist in this wrongdoing. President Trump has countered that McGahn is lying. The Committee must hear from McGahn directly.”

Attorneys for the House said the 2-to-1 ruling conflicts with a 1976 precedent in which the circuit court upheld the House’s standing to intervene in a lawsuit the Justice Department filed to block AT&T from complying with a subcommittee subpoena.

Blocking the McGahn subpoena, the House argued, is “sorely misguided” because it undermines Congress’s constitutional authority to check a president’s powers and encourages presidential stonewalling by future executives who can rest secure knowing that “direct, widescale noncompliance” is irremediable.

House Democrats went to court after Trump blocked McGahn’s testimony, saying the key presidential adviser could not be forced to answer questions or turn over documents.

Judge Thomas B. Griffith, writing for the majority, agreed with the Justice Department argument that courts should stay out of such political disputes. The court, Griffith wrote, “cannot decide this case without declaring the actions of one or the other unconstitutional, and ‘occasions for constitutional confrontation . . . should be avoided whenever possible.’ ”

In dissent, Judge Judith W. Rogers said the high court has long recognized Congress’s power to investigate and subpoena information and warned the ruling undermines legislative oversight. She noted Trump’s “sweeping categorical resistance” and refusal to cooperate with the House impeachment inquiry.

Ordering McGahn to appear before the committee, she wrote, does not require the court to choose sides because the subpoena is not a demand for McGahn to answer specific questions — only to appear in person.

The third judge on the panel, Karen LeCraft Henderson, agreed with Griffith’s overall judgment but rejected a Trump administration claim that top White House aides enjoy “absolute immunity” from compelled testimony.

The House committee subpoenaed McGahn in August before the start of formal impeachment proceedings. Lawmakers said McGahn was the “most important” witness on the question of whether Trump obstructed justice in special counsel Robert S. Mueller III’s Russia investigation.

Before Trump was acquitted in the Senate on Feb. 5, House lawyers said McGahn’s testimony was still critical to establish a pattern of alleged misconduct by the president.

In Friday’s filing, attorneys for the House argued that the panel erroneously relied on a 1997 case in which the Supreme Court later said that six members of Congress could not go to court to challenge the constitutionality of a statute. The case did not say that a whole committee backed by the full House could not sue, the filing argued.

They argued the panel’s suggestion that the standoff was strictly a “political dispute” best resolved by regular checks and balances between the legislative and executive branches “downplayed the significance of its ruling.”

The accommodations process — by which both sides typically negotiate compliance with legislative oversight demands — “operates against the backstop of potential judicial enforcement,” the House warned. Remove that backstop, and Congress’s investigative power “is essentially meaningless.”

The tools the panel suggested Congress employ — such as impeachment, withholding funds and shutting down the government, or having the House sergeant at arms arrest current and former administration officials to enforce a subpoena — “only invite further constitutional brinkmanship and are poor substitutes for judicial subpoena enforcement,” the House said.

The House also noted the legal contradiction in Trump’s recent Senate impeachment trial. Trump’s White House counsel argued that Trump could not be impeached for obstruction of Congress because the House had not first gone to court to enforce its subpoenas — a route that his administration’s Justice Department now argues would be legally invalid.

The court is expected to ask the Justice Department to respond.