The ruling is a setback for the DOJ and Flynn’s attorneys.

A federal appeals court on Monday rejected an effort by Michael Flynn, President Donald Trump‘s former national security adviser, and the Justice Department to force a lower district judge to throw out Flynn’s criminal case.

In an 8-2 ruling, the D.C. Circuit Court of Appeals said that D.C. District Judge Emmet Sullivan did not act improperly by not immediately accepting the Justice Department’s controversial push to dismiss Flynn’s case.

The court additionally said Sullivan’s appointment of an outside former judge to argue against the department was not improper, reversing the judgment of previous three-judge panel from the court which had argued Sullivan was overstepping his authorities.

Flynn pleaded guilty in late 2017 to lying to the FBI about his contacts with the former Russian ambassador before seeking to withdraw his plea early this year, alleging misconduct against the agents who investigated him.

The ruling paves the way for Sullivan to hold a hearing as he considers the DOJ’s request to dismiss Flynn’s case or reject it and move forward with sentencing, though it’s not clear whether Flynn’s attorneys or the DOJ will seek to appeal Monday’s order and prolong the case further.

A spokesperson for the Justice Department did not immediately respond to ABC News’ request for comment.

The ruling comes as at least a temporary setback for Flynn and yet another delay in a politically fraught legal battle that has dragged on since Flynn first agreed to plead guilty to charges from former special counsel Robert Mueller in December 2017.

Attorney General William Barr intervened in the case this past March as Flynn, under new legal representation, was seeking to withdraw his guilty plea.

Barr said that findings from a U.S. attorney he had tasked with reviewing the case led him to believe that Flynn’s lies during a January 2016 interview with the FBI about his contacts with the Russian ambassador were not actually relevant to a legitimate investigation, and that the case should be dropped.

Sullivan, however, did not immediately accept the DOJ’s surprise reversal in the case, and appointed an outside former judge John Gleeson to present arguments against the DOJ, as well as determine whether Flynn may have committed perjury by reneging on his guilty plea.

Flynn’s lawyers, later with support from the Justice Department, then appealed to the D.C. Circuit Court of Appeals requesting an emergency order to force Sullivan to dismiss the case.

Flynn secured a temporary victory when a three-judge panel from the court moved to overrule Sullivan, though the case was then taken up by the full court which heard arguments from the DOJ, Flynn’s attorney and an attorney for Sullivan earlier this month.

Sullivan’s attorney, Beth Wilkinson, has noted that Sullivan has not decided one way or the other on whether to sign off on the Justice Department’s motion to dismiss Flynn’s case, and that his motivation in appointing an outside judge was to simply hear all relevant arguments.