"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 acknowledged during direct examination that he overvalued at least two properties in his statements of financial condition, though he broadly represented that the statements underestimated his total net worth.

"Did you ever think that the values were off in your statement of financial condition?" state attorney Kevin Wallace asked about the document at the center of the case, which the New York attorney general has alleged contained fraudulent valuations.

"Yes, on occasion. Both high and low," Trump said, appearing to surprise Wallace, who paused to allow Trump to continue his answer.

Compared to his sons, who largely testified that they deferred to accountants and lawyers, Trump portrayed himself as an experienced businessman who "was certainly more expert than anybody else" when it came to the value of his own properties.

Asked about properties like 40 Wall Street and a retail space near Trump Tower, the former president confidently used real estate shorthand to explain why he thought certain properties were undervalued. He also repeated that his brand value -- which was not included in his financial statement -- is worth billions.

"The most valuable asset was the brand value," Trump said. "I became president because of my brand."

However, Trump acknowledged that two properties -- his triplex apartment in Trump Tower and his Seven Springs estate in New York's Westchester County -- were overvalued and had to be adjusted in his financial statement.

"I thought the apartment was overvalued when I looked at it," Trump said, appearing to refer to a $200 million correction applied to his statement after Forbes magazine reported that he falsely stated the apartment was three times its actual size.

Asked about the change in the statement, Trump acknowledged the square footage mistake, which he blamed on a broker, while also claiming that the number was "not far off" from reality when you consider the square footage of Trump Tower's roof.

"It's a mistake … [but] there's a disclaimer clause so you don't have to get sued by the attorney general of New York," Trump said.

Trump made a similar admission about the $291 million valuation of Seven Springs.

"I thought it was too high and we lowered it," Trump said, though he could not provide specifics about the changed valuation.