Judge Merchan then reviewed each of the counts against Trump to explain the People's burden of proof.

He said that in the interest of brevity, he would instruct them on Falsification of Business Records for the first count -- but not the full instruction for all 34 counts, because they are identical.

Merchan methodically walked through each of the allegedly falsified documents, listing the dates, voucher numbers, and check numbers for each of the records.

The judge said he would be happy to repeat the instructions later if the jury so requests.

Judge Merchan explained to jurors the prosecution's three theories for the unlawful means used to influence the 2016 election.

First, Merchan said that the unlawful means could include a violation of the Federal Election Campaign Act, which caps campaign contributions. Prosecutors allege that Michael Cohen's payment to Stormy Daniels exceeded the legal cap.

Second, Merchan said prosecutors argue that Trump and others falsified business records, including the bank paperwork for Essential Consultants Inc., the money wire to Daniels, and the 1099 forms related to Cohen's repayment.

Third, Merchan said the crime could be violations of tax laws related to the "grossing up" of Cohen's reimbursement to cover the taxes he would owe on the payment.

Judge Merchan tells the jury that prosecutors allege that Trump attempted to conceal a violation of New York election law by falsifying business records.

"They need not prove that the other crime was committed, aided, or concealed," Merchan said.

Prosecutors are relying on New York Election Law 17-152, which prohibits "any two or more persons who conspire to promote or prevent the election of any person to a public office by unlawful means." Prosecutors offered three theories of the "unlawful means" mentioned in that law.

Though jurors will need to agree Trump falsified records in furtherance of an additional crime in order to convict, "they need not be unanimous" on "what unlawful means" were used, Merchan said.

Judge Merchan instructed the jury about how to decipher intent, telling them it "does not require premeditation."

Intent can even be momentary, Merchan said, telling the jurors the question about how to judge intent "naturally arises."

"You must decide if the required intent can be inferred beyond a reasonable doubt," he told them.

Merchan also said earlier, "If it is proven the defendant is criminally liable for the conduct of another, the extent or degree of defendant's participation does not matter ... The defendant is as guilty of the crime as if he had personally omitted the crime."

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.