"One thing I know a lot about is the legal definition of fraud," Justice Arthur Engeron said as he gaveled court into session prior to the start of opening statements.

Engoron opened the proceedings after allowing cameras in to document the scene in the courtroom: Trump, arms folded, flanked by his legal team; Engeron on the bench; and throngs of reporters and spectators in the gallery.

"I've promised to do my best despite my lame attempts at humor," Engeron said in a brief opening statement. "I take my job very seriously."

The trial is expected to last through Dec. 22, Engeron said, and suggested he would attempt to keep a low profile after today.

"For the next three months, I hope the only words I will mutter are 'Sustained,' 'Overruled,' and 'Let's take a 10-minute break,'" he said.

Opening statements are underway in former President Trump's $250 million fraud trial.

Trump is seated between his attorneys Clifford Robert, Alina Habba and Christopher Kise.

Trump and his co-defendants face a bench trial, meaning that the sole arbiter of the case is Judge Arthur Engoron instead of a jury.

Former President Trump has taken a seat in the courtroom for the start of the trial.

"The crime is against me," he told reporters outside the courtroom before he made his way inside.

He denounced the case in now-familiar terms, criticizing state Attorney General Letitia James as she sat inside the courtroom.

Trump also accused Judge Arthur Engoron of failing to account for the full value of his real estate portfolio, asserting his Mar-a-Lago estate is worth "50 to 100 times more" than the judge's decision for partial summary judgment said last week.

"We have other properties, the same thing. So he devalued everything," Trump said. "We have among the greatest properties in the world. and I have to go through this for political reasons."

Engoron decided Trump's statements of financial condition were fraudulent, but Trump said, "We have a clause in the contract that says, essentially, buyer beware."

Former President Trump, speaking to reporters on his arrival at the lower Manhattan courthouse, said the trial is a witch hunt resulting from his standing in the presidential polls.

"This is a continuation of the greatest political witch hunt of all time," he told reporters outside the courtroom.

Trump said he is innocent of the accusations and that his portfolio has a much higher value than what the attorney general alleges.

Judge Engoron has denied a motion from the New York attorney general to preclude four expert witnesses from testifying for the defense when the defense presents it case starting on Monday.

The state had sought to preclude the four experts' testimony on the grounds that, following the testimony of the state's witnesses, the four defense witnesses were no longer relevant to the case.

"You've won the battle. We'll see if you win the war," Engoron told defense attorney Chris Kise -- though he warned Kise that he would cut off the witnesses if they try to debate facts already established in the case.

In making his ruling, Engoron reiterated his finding from his earlier summary judgment order that Donald Trump made at least ten internally contradictory claims in his statements of financial condition.

"You can't have a correct statement with these kinds of errors," Engoron said.

Kise told the court that Donald Trump Jr. will be the first witness to testify in the defense's case on Monday.

"Oh, I know him," Engoron deadpanned after the announcement.

It will mark Trump Jr.'s return to the witness box after the state put him on the stand last week.