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.

Prosecutor Josh Steinglass returned to the defense's argument that Trump "grossing up" the Cohen reimbursement -- effectively doubling the payment to account for the taxes Cohen would have to pay -- suggests the payment is suspicious for the famously frugal Trump.

"But it was worth it -- it was worth it to hide the truth about what this money was really for -- a reimbursement for the Daniels payoff," Steinglass said.

Steinglass was basically giggling to the jury as he tried to poke holes in the defense theory about the payments were legitimate expenses for legal work.

"These documents are so damning that you almost have to laugh at how Mr. Blanche explained it to you," Steinglass said.

Calling the documents "smoking guns," Steinglass said "they completely blow out of the water the defense claim."

"I'm almost speechless that they're still trying to make this argument that the it was for services rendered," Steinglass said of the payment.