A federal appeals court appeared unwilling Friday to order the immediate dismissal of the case against Michael Flynn, displaying skepticism of the former Trump national security adviser's argument that a judge overstepped his authority when he appointed an outside lawyer to oppose the Justice Department's abandonment of the prosecution.

At the nearly two-hour hearing, Flynn's lawyer and an attorney for the Justice Department faced sharp questioning from a panel of the U.S. Court of Appeals for the D.C. Circuit, whose inquiries suggested a reluctance to order U.S. District Judge Emmet Sullivan to halt his review of the government's extraordinary move to drop the case.

Flynn, who twice admitted to lying to the FBI before later trying to back out of his guilty plea, filed a petition in the D.C. Circuit last month after Sullivan declined to immediately approve the Justice Department's request to dismiss the case. Sullivan instead appointed a former federal judge in Brooklyn, John Gleeson, to review the Justice Department's move and also address whether Flynn committed perjury in the course of the court proceedings.

Gleeson earlier this week said the government's move to drop the case was a "gross abuse of prosecutorial power" designed to benefit a Trump ally.

On Friday, Judge Karen L. Henderson, a 30-year veteran of the D.C. Circuit, pushed back strongly against Flynn's bid to have the appeals court step in and order the dismissal of his prosecution.

Karen L Henderson Judge Karen LeCraft Henderson, of the U.S. Court of Appeals for the District of Columbia Circuit. (Photo: Diego M. Radzinschi/ ALM)

Henderson said it would be a "drastic remedy" for the D.C. Circuit to bring a halt to Sullivan's review and order the case's dismissal. Calling Sullivan an "old hand" and "excellent trial judge," Henderson said Sullivan might still decide to dismiss the case.

"I don't see why we don't observe regular order and allow him to rule," Henderson said.

Henderson was joined on Friday's panel by Judges Robert Wilkins and Neomi Rao, a former top Trump administration official appointed to the appeals court last year. Wilkins, a former federal trial judge who rose to the D.C. Circuit in 2014, repeatedly questioned arguments raised by Flynn's lawyer, Sidney Powell, and a top Justice Department official advocating for the appeals court to cut Sullivan's review short.

Powell, characterizing Sullivan's review as an "impermissible intrusion," argued that the case against Flynn "cannot go on any longer."

"The judge has no authority to do anything further in the case," she said.

Flynn's appeal was backed by Jeffrey Wall, a top appellate lawyer for the U.S. Justice Department, who argued Friday that Sullivan has taken up an "intrusive process" that had raised "grave, stark separation of powers concerns."

When asked why "regular order" should not be followed, with Sullivan allowed to rule, Wall said, "We would say this is an extraordinary case. We're well past regular order."

"At a minimum," Wall asserted, the D.C. Circuit should intervene in a more limited fashion and prevent Sullivan from probing the Justice Department's motives in dropping the Flynn prosecution.

"That clearly should be off the table," he said.

Sullivan turned to Beth Wilkinson, a prominent Washington trial lawyer, to defend his process before the D.C. Circuit. Wilkinson, who previously represented Justice Brett Kavanaugh during his confirmation to the Supreme Court, sought on Friday to underscore that Sullivan has not yet determined whether to dismiss Flynn's case and has appointed Gleeson strictly to better understand the scope of his authority.

"The district court is not acting as a prosecutor, nor has [Sullivan] made up his mind about the pending issues," Wilkinson said. "He is considering the government's motion and receiving briefing from all of the parties. After hearing the arguments, Judge Sullivan will do what he's called on to do on a daily basis: He'll decide the motion."

Flynn's challenge has presented the D.C. Circuit with a fresh interbranch dispute in the Trump presidency, this time pitting the administration against the judiciary in a case that has raised novel questions about the role judges play in reviewing prosecutorial decisions.

In the buildup to Friday's blockbuster argument, Republican and Democratic politicians weighed in on Flynn's case, dividing over the propriety of Sullivan's reluctance to immediately dismiss the prosecution at the request of the Justice Department. With a nod to the Trump administration's unprecedented resistance to congressional inquiries, House Democrats argued in a court filing Wednesday that Sullivan was exercising the judiciary's authority to "check prosecutorial abuses by the executive branch."

"And, here, the need for judicial oversight is even more pronounced because Attorney General [William] Barr has stonewalled congressional oversight at every turn," House Democrats said, in a brief authored by Deepak Gupta, a leading appellate lawyer in Washington.

Among Sullivan's other backers are former Watergate prosecutors and retired judges who have signed their names to court briefs asserting the judiciary's role in checking prosecutorial misconduct. In late May, a group of two dozen former federal judges questioned whether the Justice Department had acted in "bad faith" in dropping Flynn's case and argued that Sullivan has more than a mere "ministerial" role in reviewing that unusual step.

Federal judges, the group said, "are not "mere scriveners of whatever dismissal the government places before them."

Republican lawmakers, including Senate Majority Leader Mitch McConnell, argued earlier this month that Sullivan had overstepped his authority in appointing Gleeson and refusing to readily grant the Justice Department's motion to dismiss. Arguing that the Constitution "vests the power to prosecute—and the corresponding power to stop prosecuting—solely with the executive branch," the Senate Republicans said Sullivan cannot "take the prosecutorial reins" or "appoint a private party to step into the prosecution's shoes."

Sullivan has set a hearing for July 16 in Flynn's case. He has given no public indication that he will delay or otherwise change his plans for that hearing in light of Flynn's appeal.

"There's nothing wrong with him holding a hearing, as far as I know," Henderson said Friday.