A three-judge panel of the U.S. Court of Appeals for the D.C. Circuit took the unusual step of ordering Judge Emmet G. Sullivan to address the request from Flynn, President Trump’s former national security adviser, within 10 days, while also inviting the Justice Department to comment.

Sullivan last week put Flynn’s case on hold and invited outside groups and a retired federal judge to argue against the Justice Department’s pending request to toss the former three-star general’s conviction. Sullivan also asked the retired judge to examine whether Flynn may have committed perjury while pleading guilty to lying about his pre-inauguration contacts with Russia’s ambassador.

Sullivan’s move prompted Flynn’s attorneys to ask the D.C. Circuit to intervene, accusing the judge of overreaching into what they called prosecutors’ exclusive authority to decide whether to charge or drop a case, and of harboring hostility toward their client.