Judge Merchan told jurors that Michael Cohen is an "accomplice" to the alleged crime, so the jury cannot convict Trump on Cohen's testimony alone.

Even if they believe Michael Cohen, they need to rely on evidence corroborating his testimony, Merchan said.

Trump, at the defense table, appeared to perk up just a bit at this, looking up at Merchan as he delivered this information to the jury.

Judge Merchan told the jury that they have the ultimate authority in determining the truthfulness of a witness' testimony -- an instruction that might come in handy given the emphasis that defense lawyers placed on Michael Cohen's testimony, which they say includes lies.

"You will alone determine the truthfully and the accuracy of the testimony of each witness," Merchan said.

He added that the jury could either disregard the testimony of an untruthful witness entirely, or disregard part of it.

"There is no particular formula" to determine credibility, Merchan said.

"You may consider whether the witness has any interest in the outcome of the case," he said -- another matter that might weigh on jurors' minds.

"You may consider whether a witness did have, or did not have, a motive to lie," the judge said.

Trump's attorney had told the jury Cohen had an "axe to grind" against his former boss. Prosecutors partially conceded that Cohen had a motive, acknowledging that, to date, he is the only one who suffered any consequences from the matter at hand.

Trump, at the defense table, appeared to look over to the jury and offer a bit of a closed-mouth grin.

Judge Merchan instructed the jury that they cannot hold Trump's not testifying against him.

"Defendant is not required to prove that he is not guilty," he said.

"The defendant is not required to prove or disprove anything," said the judge.

Judge Merchan told the jury that they should not speculate about the sentence or punishment in the case.

"It will be my responsibility to impose an appropriate sentence," Merchan said.

The judge also had to advise the jury about this yesterday after defense lawyer Todd Blanche argued that the jury "cannot send somebody to prison" based on Michael Cohen's testimony.

The jury appears to be laser focused on Merchan during the charge. Half of the jurors appear to be taking notes.

Describing his own closing as "summation that never ends," prosecutor Josh Steinglass told the jury that in order to convict, they will have to find the defendant "has to have had the intent to defraud," but didn't need to actually make the records himself.

"Point is, Trump doesn't have to do each of these acts himself -- he can act in concert with others," Steinglass said. "He set in motion a chain of events that led to the creation of the false business records,.

The defense objected to that statement.

"I'll explain the law," Judge Merchan said.

Steinglass said the underlying crime they are alleging as part of the falsifying records charge is that Trump violated New York state election law.

Trump committed "election fraud, by any means necessary -- lawful and unlawful," Steinglass said, telling jurors there is a "mountain of evidence" to prove it.

Judge Merchan sustained another objection from the defense regarding Steinglass' effort to explain the law of the case.