How Judge Aileen Cannon, a Trump Appointee, Could Influence Documents Case

Jack Smith, the special counsel handling the documents investigation into former President Donald J. Trump, vowed to seek “a speedy trial.” But that will be up to Judge Aileen M. Cannon, who will wield considerable power over its calendar, evidence and jury.

Last year, Judge Cannon, a Trump appointee, briefly disrupted the documents investigation by issuing rulings favorable to him when he challenged the F.B.I.’s search of his Florida club and estate, Mar-a-Lago, before a conservative appeals court ruled that she never had legal authority to intervene.

It remains to be seen how she will handle her second turn in the spotlight. The scope of her role before the trial also is unclear: She is not presiding over Mr. Trump’s initial hearing on Tuesday, and could refer some pretrial motions to a magistrate judge who works under her. But here is a closer look at how her decisions as the judge presiding over the trial — like on what can be included and excluded — could affect the case.

Slowing the Calendar

Mr. Trump has long pursued a strategy of trying to delay legal proceedings against him to run out the clock. If the trial can be put off until after the 2024 presidential election, he or another Republican nominee could enter office and shut down the case.

“I think the Department of Justice will do everything in their power to bring the case as soon as possible, but it will be a challenge to bring it before we are well into the primaries,” said Brandon L. Van Grack, a former federal prosecutor who has worked on complex cases involving national security and classified material.

He added, “These issues are incredibly important to understand because we are talking a case that could influence an election — and more than just the general election.”

Classified Evidence

Before the trial begins, there is almost certain to be extensive fights behind closed doors over the use of classified evidence, a matter governed by the Classified Information Procedures Act, or CIPA. The law was intended to reduce the opportunities for so-called graymail in criminal cases involving national security, in which defendants threaten to expose sensitive secrets unless prosecutors drop charges against them.

One potential issue: whether the government has to publicly expose all 31 classified documents that are the basis of the 31 counts against Mr. Trump for illegally retaining national-security secrets. Their contents are key evidence for whether they qualify as the type of information protected by the Espionage Act.

CIPA establishes court procedures to sometimes shield sensitive information from the public, including by redacting some documents or substituting summaries. But defense lawyers can argue that they need to discuss their full contents in open court for the trial to be fair.

If Mr. Smith obtained the intelligence community’s consent to use those 31 documents based on assurances that he would keep them from broader public dissemination, any rulings by Judge Cannon requiring them to be shown in open court could lead the government to instead drop some of the charges based on those documents.

Mr. Trump’s defense lawyers are also likely to argue that the government is obligated to turn over related classified material in the “discovery” phase, and they may want to use some of those records in open court, too. Either side can appeal Judge Cannon’s decisions about these matters before the trial, creating additional opportunities for delay.

Attorney-Client Evidence

In laying out charges that Mr. Trump obstructed the government’s efforts to retrieve the documents and caused one of his lawyers to make a false statement to the Justice Department, federal prosecutors described Mr. Trump’s interactions with his legal team. These include how he apparently suggested destroying classified documents and hid from his lawyers that he had boxes of files removed from a storage area after a subpoena.

Normally, prosecutors cannot subpoena defense lawyers and force them to testify or turn over notes about their client. Under attorney-client privilege, the confidentiality of such discussions and work is protected.

That privilege is meant to protect the rights of people who are in trouble over a past potential offense. People need to be able to talk candidly with their lawyers about what happened to understand their options. That would be impossible if whatever people admitted could be used against them as evidence in court.

But there is an exception: when attorney-client communications are part of continuing or future crimes. If judges think there is sufficient evidence to activate this “crime-fraud exception,” they will uphold a subpoena forcing the defense lawyers to provide evidence about what they and their clients said to each other.

During the investigation, Judge Beryl A. Howell of the Federal District Court for the District of Columbia ruled that the exception applied, forcing Mr. Trump’s lawyers to provide information to the grand jury. But Judge Cannon is not bound by Judge Howell’s decisions when it comes to what information should be presented to a jury.

During pretrial motions, if Mr. Trump’s lawyers ask Judge Cannon to suppress the evidence to protect attorney-client privilege and she does so, prosecutors could appeal — but that would further delay the case.

If she were to defer a decision until after the trial has started, prosecutors could interrupt the trial and try to appeal using an extraordinary and rarely used tactic called a writ of mandamus, said Paul F. Rothstein, a Georgetown University law professor and specialist in criminal procedure.

Prosecutorial Misconduct Claims

Mr. Trump and his legal team have signaled that they will attack prosecutors and investigators. That could mean pretrial motions to dismiss the charges based on any allegations that prosecutors committed misconduct like improperly pressuring witnesses, vindictive prosecution and selective prosecution.

It is routine for defendants to make such claims, and it is routine for judges to briefly look at and reject them. The standards for finding a violation are very high. But if Judge Cannon entertained such claims, she could demand information from prosecutors, hold hearings and essentially put the investigators on trial before Mr. Trump faces any jury.

Jury Selection

Prosecutors and defense lawyers will have a certain number of “peremptory” challenges in which they can block someone from being on the jury without stating a basis. But they also have unlimited challenges to potential jurors “for cause” if they can point to signs that those people are biased. Judge Cannon will have the power to accept or reject any “for cause” challenges, potentially tilting the composition of the jury.

‘Rule 29’ Motions to Acquit

After the prosecution and defense present evidence, the defense can make a so-called Rule 29 motion asking Judge Cannon to acquit Mr. Trump on one or more of the charges, arguing that the evidence from prosecutors was deficient.

She could do so in two ways: acquit Mr. Trump right away, or let the matter go to the jury and then enter an acquittal only if the jury instead wanted to convict.

If the judge waited, leaving a chance for the jury to vote for conviction, then prosecutors could appeal the judge’s acquittal order and get it reversed, said Julie O’Sullivan, a Georgetown University law professor and former federal prosecutor. But if the judge declared the defendant acquitted before any verdict by a jury, she said, that outcome would be final and prosecutors could not appeal it.

Hung Jury

In federal criminal trials, all 12 jurors must unanimously agree that prosecutors have proved each of the elements of a crime beyond a reasonable doubt to convict.

If the jury can never reach consensus, the result is a mistrial, and prosecutors would then have to decide whether to start over with a new trial. Judges typically try to avoid that by encouraging jurors to resolve their disagreements and reach consensus with a holdout, and by giving them more time to deliberate. But if there is an early disagreement, a judge could also kneecap the government by immediately declaring a mistrial.