A federal judge on Friday delayed the start of a criminal contempt of Congress trial of Peter Navarro, amid questions about a potential defense related to former President Donald Trump and executive privilege.

Navarro, a White House adviser during the Trump administration, had been scheduled to go to trial next week on two charges that he refused to comply with a subpoena from the House select committee investigating the Jan. 6, 2021, attack on the Capitol.

Instead, Judge Amit P. Mehta of the U.S. District Court for the District of Columbia asked attorneys for the Justice Department and Navarro to address complicated questions of when executive privilege applies for a former aide to a former president.

At a hearing Friday, Mehta said he felt like “we are in uncharted territory” over how to handle such a potential defense at trial.

Mehta already has declined to dismiss the charges entirely on Navarro’s claim that he did not comply with the subpoena because of executive privilege, which gives the president the power to withhold certain documents from Congress.

As part of that effort, Navarro submitted a letter from an attorney representing Trump, which said Navarro had an “obligation to assert executive privilege” on Trump’s behalf when presented with the select committee subpoena.

Mehta on Friday said the letter was “notable for what it does not say.”

“It doesn’t say Mr. Trump ever instructed Mr. Navarro to invoke executive privilege with respect to the Jan. 6 select committee,” Mehta said.

But Mehta said Navarro may still be able to argue before the jury that Trump had specifically instructed him to invoke executive privilege in response to the Jan. 6 select committee’s subpoena.

The government and Navarro’s attorneys spent most of an hour discussing with Mehta whether Navarro could still assert that as a defense, whether it was better to settle it separately before trial started, and how jury members could be instructed to consider such a claim in their deliberations.

The Justice Department argued Friday that because Navarro’s executive privilege claim had been rejected before the trial, he should be precluded from presenting that evidence to the jury.

“It is unprecedented for a jury to be asked to decide whether executive privilege has been invoked,” DOJ attorney Elizabeth Aloi said.

But Mehta differentiated between the pretrial motions and what Navarro could present to the jury.

Mehta already delayed Navarro’s trial once last year because of a scheduling conflict with another trial related to the Jan. 6 attack.

The Justice Department indicted Navarro last year, and Navarro, if convicted, faces a minimum of 30 days in prison on each count, up to a maximum of one year.

The House voted to refer Navarro for criminal contempt charges last year, one of five such witnesses. The DOJ indicted only two: Navarro and former White House adviser Steve Bannon.

Bannon was convicted on two counts of contempt following a trial last year, the first such conviction in decades.

Bannon has appealed his conviction in a case currently pending before the U.S. Court of Appeals for the District of Columbia Circuit.