The challenge to the legality of special counsel Jack Smith's appointment kicked off a three-day hearing on Friday that is set to continue next week and bring further delays to a criminal case that had been scheduled for trial last month but has been snarled by a pile-up of unresolved legal disputes.
The motion questioning Smith's selection by the Justice Department is one of multiple challenges to the indictment the defence has raised, so far unsuccessfully, in the year since the charges were brought.
US District Judge Aileen Cannon heard hours of arguments on Friday from lawyers for both sides, with Trump lawyer Emil Bove asserting that the Justice Department risked creating a "shadow government" through the appointment of special counsels to prosecute select criminal cases.
Prosecutors say there was nothing improper or unusual about Smith's appointment, with James Pearce, a member of Smith's team at one point saying: "We are in compliance. We have complied with all of the department's policies."
Cannon did not immediately rule but in an apparent sign that she was taking seriously the Trump team motion, grilled Pearce on what oversight role Attorney General Merrick Garland - who appointed Smith - had in seeking the indictment.
Prosecutor Jack Smith charged Donald Trump with hoarding classified documents at his estate. (AP PHOTO)
Pearce said he was not in a position to answer the question but noted "I don't want to make it seem like I'm hiding something".
Even as Smith's team looks to press forward on a prosecution seen by many legal experts as the most straightforward and clear-cut of the four prosecutions against Trump, Friday's arguments did not concern the allegations against the former president.
They centred instead on arcane regulations governing the appointment of Justice Department special counsels like Smith, reflecting the judge's continued willingness to entertain defence arguments that prosecutors assert are frivolous and meritless, contributing to the indefinite cancellation of a trial date.
At issue in Friday's hearing is a Trump team claim that Smith was illegally appointed in November 2022 by Garland because he was not first approved by Congress and because the special counsel office that he was assigned to lead was not also created by Congress.
Smith's team has said Garland was fully empowered as the head of the Justice Department to make the appointment and to delegate prosecutorial decisions to him.
The hearing continues on Monday when the two sides again discuss matters related to Smith's appointment, as well as a limited gag order that prosecutors have requested to bar Trump from comments they fear could endanger the safety of FBI agents and other law enforcement officials involved in the case.
