ALBANY, N.Y. (AP) — A judge disqualified a federal prosecutor from overseeing investigations into New York Attorney General Letitia James, ruling Thursday that he had been serving in his post unlawfully when he requested subpoenas.

U.S. District Judge Lorna G. Schofield blocked subpoenas requested by John Sarcone, the acting U.S. attorney for the Northern District of New York.

“The subpoenas are unenforceable due to a threshold defect: Mr. Sarcone was not lawfully serving as Acting U.S. Attorney when the subpoenas were issued,” the judge wrote.

James, a Democrat, had challenged Sarcone’s authority after he issued subpoenas seeking information about lawsuits she filed against President Donald Trump, claiming he had committed fraud in his business dealings, and separately against the National Rifle Association and some of its former leaders.

Justice Department lawyers say Sarcone was appointed properly and that the subpoenas were valid. James claims the inquiry into her lawsuits is part of a campaign of baseless investigations and prosecutions of Trump’s perceived enemies.

The ruling is the latest to address the legality of unusual maneuvers the Trump administration has performed to try and keep its favored candidates for U.S. attorney in those jobs indefinitely, without going through the usual process of getting them confirmed in the U.S. Senate.