Another federal judge heard arguments Thursday about the legitimacy of a top Trump administration prosecutor as New York Attorney General Letitia James challenged the authority of the acting U.S. attorney probing two of her high-profile cases.

The court hearing focusing on the role of John Sarcone, who is acting as U.S. attorney for northern New York, comes as President Donald Trump’s effort to install political loyalists as federal prosecutors has run into a legal buzz saw. Judges have ruled recently that his handpicked U.S. attorneys for New Jersey, eastern Virginia, Nevada and Los Angeles were all serving unlawfully.

James, a Democrat, is challenging Sarcone’s authority to oversee a Justice Department investigation into regulatory lawsuits she filed against Trump and the National Rifle Association. It’s one of several arguments she is making to block subpoenas issued as part of the probe, which her lawyers say is part of a campaign of baseless investigations and prosecutions of Trump’s perceived enemies.

Her attorney Hailyn Chen argued in court that since Sarcone lacks legitimate authority to act as U.S. attorney, legal steps taken by him in that capacity — like the subpoenas — are unlawful. In response to a question from U.S. District Judge Lorna G. Schofield, Chen said Sarcone should be disqualified from the investigation and the office.