McGahn was a central figure in the Mueller investigation.

A federal appeals court ruled Friday that House Democrats can sue to enforce a congressional subpoena demanding testimony from former White House counsel Don McGahn.

Friday’s ruling did not address what kind of questions McGahn would be required to answer from the House Judiciary Committee and kicked back other legal issues in the case for a three-judge panel to resolve — likely delaying any possible appearance by McGahn in front of the committee before the subpoena’s expiration.

McGahn was a central figure in several key episodes singled out by former special counsel Robert Mueller that Democrats argued amounted to attempted obstruction of justice by President Donald Trump in the Russia investigation.

While McGahn left the White House in fall of 2018, Trump ordered him, in addition to other current and former officials, not to comply with Democrats’ request for testimony in their investigations regarding Trump’s conduct.

While Democrats eventually opted not to incorporate allegations from the Mueller investigation into their impeachment inquiry of President Donald Trump that ended in his acquittal early this year, lawyers for the Judiciary Committee have continued pressing for enforcement of their subpoena against McGahn — arguing his testimony still remained relevant to their oversight duties.

In its 7-2 ruling, the full D.C. Circuit Court of Appeals said Congress would suffer “concrete” injury by being deprived of McGahn’s testimony in the Judiciary Committee’s investigation into allegations of misconduct by Trump.

“[Congress] cannot conduct effective oversight of the federal government without detailed information about the operations of its departments and agencies,” D.C. Circuit Judge Judith Rogers said Friday in her majority opinion. “And it cannot undertake impeachment proceedings without knowing how the official in question has discharged his or her constitutional responsibilities.”

In a statement reacting to the ruling, the Justice Department said it would continue to argue for dismissal of the case, as well as a connected case brought by House Democrats seeking permission to sue the Trump administration over its use of emergency funds to build the wall along the U.S.-Mexico border.

“While we strongly disagree with the standing ruling in McGahn, the [full] court properly recognized that we have additional threshold grounds for dismissal of both cases,” DOJ spokesperson Kerri Kupec said. “We intend to vigorously press those arguments before the panels hearing those cases.”

In a dissenting opinion, Circuit Judge Thomas Griffith argued the ruling would “supplant negotiation with litigation, making it harder for Congress to secure the information it needs.”

“The Committee likely won’t even get what it wants in this case. Because the majority declines to decide whether the Committee has a cause of action and whether it should prevail on the merits, the chances that the Committee hears McGahn’s testimony anytime soon are vanishingly slim,” Griffith said.