Former President Donald J. Trump’s defense team tried on Friday to persuade the judge overseeing the national security documents case to dismiss the indictment, pushing a long-shot argument that the special counsel, Jack Smith, was not properly appointed.
Such defense motions are routinely denied in federal cases involving special counsels. But the judge presiding over this case, Aileen M. Cannon, has given Mr. Trump’s request extra import by holding hearings and allowing three outside lawyers time in court to make additional arguments about whether there is a constitutional mechanism for naming special counsels.
“This has been very illuminating and helpful,” Judge Cannon said at the close of about four hours of arguments and a steady beat of her own questions, which often began with, “Would you agree that.”
Mr. Trump’s team argued that the attorney general lacks constitutional authority to appoint someone with the powers of a special counsel. “The text of these statutes really matters,” said Emil Bove, one of Mr. Trump’s lawyers. He also argued that Mr. Smith should have been confirmed by the Senate because his position is so powerful.
Prosecutors argued that well-established precedents demonstrate that the attorney general does have that power, citing a string of court decisions upholding special counsel investigations. “We’re interpreting statutory terms consistent with the Constitution,” said James I. Pearce, a member of the special counsel’s team.
Judge Cannon’s questions addressed language in specific laws, past precedents and excerpts from lawyers’ written briefs. At times on Friday, her courtroom sounded like a university seminar on the history of the Justice Department, national scandals that have drawn special counsels and the various interpretations of the meaning of words in decades-old laws.
Mr. Trump and his two co-defendants in the case were not in the courtroom on Friday. Neither was Mr. Smith.
Two of the outside lawyers argued in support of Mr. Trump’s request that the case be dismissed — Josh Blackman on behalf of the Landmark Legal Foundation, a nonprofit legal group that advocates limited government, and Gene C. Schaerr, who represented two former Republican attorneys general, the conservative group Citizens United and Citizens United Foundation.
Arguing against the dismissal motion was Matthew A. Seligman, speaking for constitutional lawyers, former government officials and the nonprofit group State Democracy Defenders Action.
All of the outside lawyers had previously filed “amicus,” or friend-of-the-court, briefs, which are common in appellate cases but rarely allowed at the trial court level.
Judge Cannon, who was nominated to the bench by Mr. Trump and confirmed at the end of his time in office, has given courtroom time to several issues that other judges might have ruled on from the bench. She has also accumulated a growing pile of issues she has yet to decide on.
“The legal issues and questions she claims to be struggling with are quite basic,” said Joëlle Anne Moreno, a law professor at Florida International University. “Most judges would consider many of the defense arguments to be meritless.”
Mr. Trump’s lawyers filed their motion to dismiss the indictment over the constitutionality of Mr. Smith’s appointment in February. Since then, two other Trump-appointed judges in different districts denied similar motions relating to the prosecutions of Hunter Biden, President Biden’s son, on separate tax and gun charges. Mr. Pearce said six other federal judges have come to the same conclusion.
Attorney General Merrick B. Garland appointed Jack Smith as special counsel in November 2022 to investigate whether Mr. Trump broke the law in his efforts to overturn the results of the 2020 election. He also gave Mr. Smith the authority to investigate Mr. Trump’s retention of national security documents after he left office.
A special counsel is typically named in situations where an investigation could raise the appearance of a conflict of interest for the department or when there is another reason it would benefit the public to bring in an outside prosecutor. In addition to Mr. Smith, Mr. Garland named two other special counsels, one for the Hunter Biden investigation and one for the inquiry into President Biden’s own handling of classified documents.
“If no special counsel is appointed, and it’s a federal crime that is being investigated or prosecuted, regular federal prosecutors are assigned,” Paul Butler, a former federal prosecutor in the Justice Department’s public integrity section, said in an interview. “And based on my experience, that works out fine.”
Mr. Trump was indicted last June on charges of illegally holding on to classified documents after he left office and then obstructing the government’s repeated efforts to retrieve them.
The debate over Mr. Smith’s appointment will continue on Monday, when Mr. Trump’s lawyers will argue that Mr. Smith is being improperly compensated. Judge Cannon asked both parties to consider a recent Supreme Court decision over how an independent government agency is funded. That case has no apparent connection to the appointment of a special counsel.
On Monday afternoon, the prosecution is expected to argue that the conditions of Mr. Trump’s release should be changed to restrain him from making statements that could put F.B.I. agents involved in the 2022 search of Mar-a-Lago, Mr. Trump’s Florida estate, in danger.
Then, on Tuesday, Judge Cannon plans to hold a hearing about the F.B.I. search of Mar-a-Lago, and the defense’s claim that prosecutors violated attorney-client privileges.
Judge Cannon has indefinitely postponed setting a date for the trial.