Donald Trump faced forward and did not appear to make eye contact with any jurors as they entered the courtroom and took their seats in the jury box.

Before any of the lawyers in the case could speak a word, Judge Merchan launched into a lengthy speech outlining how the trial will work.

"We are about to begin the trial of People of the State of New York v. Donald Trump," Merchan told the 12 jurors and six alternates.

Merchan emphasized that the burden of proof rests on the prosecutors and that jurors should presume that Trump is innocent. A guilty verdict requires that each juror determines that the state proved their case beyond a reasonable doubt, Merchan said.

"The defendant is presumed to be innocent," Merchan said. "It is not sufficient to prove that the defendant is probably guilty."

Merchan attempted to set expectations for the jurors, only two of which have ever served on a jury before. For example, Merchan told the jurors not to expect the lawyers to launch into lengthy speeches outside of the opening and closing statements.

"That happens in TV and in movies, but it doesn't happen in real trials," Merchan said.

Judge Juan Merchan ruled that if Trump takes the stand, prosecutors can question him about a number of previous legal issues -- but the judge limited the scope of the cases and the extent to which prosecutors can question him about the facts of those cases.

The ruling is a mixed bag for Trump, who had sought to entirely block questioning on these previous issues if he takes the stand.

Judge Merchan ruled that Trump can be questioned by the DA's office on six determinations from four previous proceedings, including aspects of his New York civil fraud case and the gag order violations there, as well as both verdicts in the E. Jean Carroll cases and the 2018 Trump Foundation case.

Prosecutors had originally asked to question Trump about six different proceedings with 13 total determinations.

Merchan said with his ruling, he has "greatly curtailed" how much prosecutors can discuss the underlying facts of those cases.

"The court cautions the defendant that this Sandoval ruling is a shield, not a sword," Merchan said.

Prosecutors told Judge Merchan that they need 40 minutes for their opening statements.

Defense attorneys told the judge they need 25 minutes.

The judge also announced that court will break at 12:30 p.m. ET today, after a juror had a toothache and got an emergency appointment this afternoon.

Court had already been scheduled to end early today, at 2 p.m. ET, due to the Passover holiday.

Judge Juan Merchan announced there is an issue with Juror No. 9 -- who, according to Merchan, "was concerned about media attention" of the case. According to Merchan, the juror "wasn't 100% sure" they could serve.

Merchan said they would speak to the juror in chambers to "find out what the issue is and see if this juror can continue to serve."

After a brief sidebar, the judge announced: “Juror No. 9 is going to remain with us.”

There are six alternate jurors seated in case any of the 12 jurors cannot serve.

The prospective alternate who said her father was a friend of Chris Christie's broke down crying during the individual questioning of prospective jurors, telling assistant DA Susan Hoffinger, "This is so much more stressful than I thought it would be."

Hoffinger was quizzing potential alternates about their views of the burden of proof that prosecutors are required to meet.

"I have to be honest, I feel so nervous and anxious right now," the woman said, breaking into tears. "I'm sorry, I thought I could do this. I wouldn't want someone who feels this way to judge my case."

Judge Merchan called her up to the bench for a private conversation and excused her from the pool.

When the questioning resumed, another prospective alternate turned the tables on Hoffinger. "May I ask you a question?" he said. "The burden of proof is subjective to each individual juror?"

Hoffinger explained that "there is only one burden of proof" and that prosecutors are obligated to prove Trump's guilt beyond a reasonable doubt.

The man said he accepted that, and that he would not hold prosecutors to an even higher standard because Trump is a former president.