"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.

Donald Trump Jr. struggled to answer questions when pressed about why former Trump Organization CFO Allen Weisselberg departed the family's firm.

"Because some legal issues he got himself into," Trump Jr. said, declining to offer specifics about Weisselberg's guilty plea on tax evasion charges last year.

Previously giving lengthy answers to questions about his background and even smiling with the judge, Trump Jr. appeared tense on the witness stand as he answered questions about Weisselberg.

"The specific event was he was indicted," Trump Jr. said.

He added that when began working for the Trump Organization as an executive vice president in the 2010s, Weisselberg outranked him. Trump Jr. would seek Weisselberg's approval for certain business decisions such as refinancing loans.

"Who is above you in your role as an executive vice president in the Trump Organization?" state attorney Colleen Faherty asked.

"Obviously I would have reported to my father in that period of time … people like Allen Weisselberg would have still been senior to me," Trump Jr. said of that time period.

Trump Jr. said he gained more responsibility in 2016 when his father became president and he was named a trustee of his father's revocable trust. He said that he, Weisselberg and his brother Eric Trump became a kind of triumvirate running the Trump Organization.

"We stopped reporting to my father on decisions involving the business," Trump Jr. said.

That relationship broke down once Weisselberg got himself into "legal issues," Trump Jr. said. He testified that he could not recall the circumstances of Weisselberg's exit, including the multimillion-dollar severance deal that Weisselberg received, which Weisselberg faced questions about during his own testimony earlier this month.

"I have no knowledge of the specifics of how it happened. He is no longer working at the Trump Organization," Trump Jr. said of the former CFO.