The U.S. Justice Department on Monday urged an Arizona federal judge to end the criminal contempt prosecution of former sheriff Joe Arpaio, the recipient of a presidential pardon that critics contend undermined judicial power.

U.S. District Judge Susan Bolton sought the government's views in advance of a hearing that's set for Oct. 4. The Justice Department's Public Integrity Section, based in Washington, filed its brief agreeing with Arpaio that the judge should vacate all orders and dismiss the case as moot.

Bolton found Arpaio in criminal contempt in July for violating a civil order that forbid him and deputy sheriffs from detaining people based on the suspicion of being an undocumented immigrant. Bolton concluded that Arpaio “willfully violated an order of the court.” Arpaio was awaiting sentencing when President Donald Trump issued the pardon on Aug. 25.

In the brief, the Justice Department told the court that Trump's decision to grant a “full and unconditional” pardon for Arpaio's conviction ends the prosecution.

“The presidential pardon removes any punitive consequences that would otherwise flow from defendant's non-final conviction and therefore renders the case moot,” the government's legal team said in its brief. Annalou Tirol is the acting chief of the Public Integrity Section, a component of the Justice Department's Criminal Division.

The pardon moots the case because Arpaio faces no punishment or legal disabilities as a result of his guilty conviction, according to the Justice Department.

One legal scholar has said Bolton is certain to dismiss the case, but whether she will vacate the conviction is a separate issue. “Arpaio is asking for a complete expungement of the case, which is more than the pardon entitles him to,” Bernadette Meyler of Stanford Law School told Bloomberg Politics in August.

The Roderick and Solange MacArthur Justice Center at Northwestern Pritzker School of Law filed a brief Monday that asked Bolton not to vacate Arpaio's conviction.

“Eviscerating this court's power to enforce constitutional rights is precisely what the pardon will do if given effect,” David Shapiro, director of the justice center's appellate litigation, said in the brief. “Such an outcome would not be limited to this court. It would, by design, diminish the judicial power of every federal court to enforce constitutional rights.”

Law Scholars Weigh In

Several other amicus briefs were filed Monday, including one from UC Berkeley School of Law Dean Erwin Chemerinsky, Michael Tigar and Jane Tigar. Michael Tigar, whose son Jon Tigar is a judge on the U.S. District Court for the Northern District of California, is professor emeritus at Duke University School of Law and a former Williams & Connolly partner. He is married to Jane, a lawyer who focuses on human rights work.

“The President's purported pardon of Mr. Arpaio is void,” the amicus brief, filed by a team from Osborn Maledon, argued. The scholars contend Arpaio's underlying crime—contempt of court—is not an “offense” within the meaning of the president's constitutional power to grant pardons.

Arpaio has threatened to appeal if the judge denies his request. An appeal could trigger a legal and constitutional fight over the scope of the president's pardon power.