Federal court proceedings throughout New Jersey were abruptly canceled on Monday because of uncertainty over whether Alina Habba had the authority to serve as acting U.S. attorney — a title she was given last week as her interim appointment as the state’s top federal prosecutor was about to expire.
Pretrial conferences and hearings set for defendants to enter pleas were called off, according to four lawyers who received word that their clients’ scheduled court appearances had been canceled. A grand jury that was expected to meet to consider indicting defendants on new criminal charges was put on hold. And a drug trial that was set to start Aug. 4 in Camden, N.J., was moved to Pennsylvania after a lawyer representing one of the defendants filed a motion arguing that Ms. Habba’s prosecutorial authority was unconstitutional.
“I’ve never seen anything like this,” said Maria Noto, a former president of the Association of Criminal Defense Lawyers of New Jersey. “We’re all incredulous.”
Ms. Noto said she was notified on Monday that a judge had canceled a hearing for a client who expected to enter a guilty plea later this week.
“It seems as if anyone who had anything scheduled has heard that whatever proceeding they had, had been adjourned with no new date for now,” Ms. Noto said.
The confusion and cancellations in New Jersey’s courts followed a high-stakes battle last week between the Trump administration and the state’s Federal District Court judges over who would lead the U.S. attorney’s office. A panel of district judges had selected a veteran New Jersey prosecutor, Desiree L. Grace, to take over after Ms. Habba’s term as interim U.S. attorney expired last week, as they are authorized by law to do.
But Justice Department officials quickly fired Ms. Grace, a widely respected prosecutor whom Ms. Habba had appointed as her top deputy — creating a vacancy that Ms. Habba herself was named to fill days later. Then, Ms. Habba, as the most senior official in the office, was elevated to the role of acting U.S. attorney for at least the next 210 days.
One of the primary legal questions surrounding Ms. Habba’s tenure stems from a federal statute that bars candidates from serving as an acting U.S. attorney if they have been nominated to hold the job permanently.
Mr. Trump withdrew Ms. Habba’s nomination, which was pending before the U.S. Senate, before she was appointed acting U.S. attorney on Thursday, according to a Justice Department spokesman.
But legal scholars immediately began questioning whether Ms. Habba, President Trump’s former personal lawyer, was disqualified from holding the job because her name had already been submitted for Senate confirmation.
The statute states that “a person may not serve as an acting officer” if the president “submits a nomination of such person to the Senate for appointment to such office.”
“Withdrawing the nomination doesn’t change the fact that it was submitted,” Stephen I. Vladeck, a professor at the Georgetown University Law Center, wrote on social media.
Thomas Mirigliano, the lawyer who filed Monday’s legal motion challenging Ms. Habba’s authority, said the drug trial had been moved out of concern that the murkiness of Ms. Habba’s standing might undermine the proceedings.
In court, Judge Edward S. Kiel described Ms. Mirigliano’s motion as a “nonfrivolous argument” and indicated that other federal judges were prepared to temporarily halt court proceedings in New Jersey while the matter of Ms. Habba’s authority was being considered.
“At this point, as I said, you’ll see, generally, that a lot of judges will not be hearing any criminal cases that are of a non-urgent matter,” Judge Kiel said, according to a transcript of the proceeding.
He explained that any legal decision-making conducted while Ms. Habba’s status was being challenged might unravel if the court grants Mr. Mirigliano’s motion, which argues that Ms. Habba was appointed to the job unlawfully through “irregular procedural maneuvers.”
“Because, for example, if we take a plea today, and that motion is granted, I don’t think that the plea colloquy today and what the United States attorney does here in this case would be effective, and we would have to redo all of those things,” Judge Kiel said in a Camden courtroom.
A spokesman for New Jersey’s federal court system had no immediate comment. Ms. Habba’s office did not respond to emails, calls or texts seeking comment.
In court, however, the government indicated that it intended to challenge Mr. Mirigliano’s motion “in short order.”
Later on Monday, Michael A. Chagares, the chief judge for the U.S. Court of Appeals for the Third Circuit, signed the order moving the drug trial outside the District of New Jersey. The one-sentence order stated that the trial was being moved to the Middle District of Pennsylvania “in the public interest,” without additional explanation.
Margaret A. Wiegand, the circuit executive, said that she had no information beyond the order about the decision, or about whether other cases might be affected.
A private electronic message board popular with criminal defense lawyers in New Jersey began filling Monday afternoon with notes about cancellations and questions about whether anyone knew what was going on, according to a half-dozen people familiar with the exchanges.
In one message reviewed by The New York Times, an official with the office of the Federal Public Defender in New Jersey, which represents clients who cannot afford legal counsel, wrote that the judges had been advised to delay proceedings until the issue relating to Ms. Habba’s authority could be decided “expeditiously.”
Ms. Habba took over as interim U.S. attorney in March after Mr. Trump, on social media, said that he had appointed her to the post “effective immediately.” The attorney general, Pam Bondi, swore her in several days later.
Ms. Habba is one of several of Mr. Trump’s former defense lawyers to serve in top Justice Department positions. And she has said that she hoped to use the traditionally nonpartisan position to help elect Republicans and “turn New Jersey red.”
She has since pursued several investigations of prominent Democrats.
In May, Ms. Habba, 41, charged Mayor Ras J. Baraka of Newark and Representative LaMonica McIver, both Democrats, after a clash with federal immigration agents outside a Newark detention center the officials were seeking to tour.
Ten days later, Ms. Habba moved to drop the trespassing charge Mr. Baraka faced — a sequence of events that led a federal judge to publicly criticize New Jersey’s U.S. attorney’s office. Mr. Baraka is now suing Ms. Habba for malicious prosecution.
Ms. Habba had also directed prosecutors in her office to investigate New Jersey’s Democratic governor, Philip D. Murphy, and the state’s attorney general, Matthew J. Platkin, over a policy that limits how much help local police can provide federal immigration officers.
Jonah E. Bromwich contributed reporting.