An attorney for Donald Trump's adult sons, Eric Trump and Donald Trump Jr., added a brief opening statement of his own, defending his clients from accusations of wrongdoing.

"There was never a material misrepresentation made by Eric Trump or Donald Trump Jr.," said Clifford Robert, the attorney for Trump's adult sons, who help run the Trump Organization.

Robert said he disagrees "with just about everything" the state's prosecutor said in his opening remarks, and took aim at the state's star witness.

"Their major linchpin is Michael Cohen, a guy who lies to everyone," Robert said of the former Trump attorney.

Attorney General Letitia James "is setting a very dangerous precedent for any business in the state of New York," warned Trump attorney Alina Habba in her opening statement.

Habba told the court she hadn't planned to make opening remarks, but that she felt moved to speak after hearing the state present its own opening statement. Habba accused the attorney general of targeting Trump before taking office, claiming the investigation and lawsuit were personal in nature.

"We are attacking a sitting president and two of his children and his employees for a statement of financial condition which is frankly worth less than what they are worth," Habba said.

Habba reiterated many of the points made earlier by co-counsel Christopher Kise, highlighting the fact that "these lenders made money," and arguing that "real estate is malleable -- the values change."

After Habba concluded her remarks, Judge Engeron engaged her in a series of follow-up questions, asking about her claim that the property appraisals at issue were "undervalued" by prosecutors.

Habba replied that "the Trump brand is worth something."

Former President Trump's defense counsel will present a "very different picture of the evidence" than the prosecution alleges, and will demonstrate that "there are many ways to value assets," according to opening remarks from Christopher Kise, Trump's lead attorney.

"We think the evidence is going to establish … President Trump has made billions of dollars building one of the most successful real estate empires in the world," Kise said, reiterating sentiments he conveyed in pretrial motions.

Kise offered a glimpse into the former president's defense, including plans to present testimony from a New York University professor who will explain that "there is no one generally accepted procedure to determine the estimated current value" of a property.

Other defense witnesses, including four Deutsche Bank officers who were involved in approving Trump's loans, will explain how they were able to craft their own independent risk analyses meant to mitigate the claims of fraud that are core to the state's case.

"Anyone committing fraud does not tell the other side, 'Please do your own analysis,'" Kise said regarding Trump's instructions to lenders.

Kise also previewed plans to undermine the state's key witness, former Trump attorney Michael Cohen, who Kise said has "lied to everyone and anyone he has come in contact with."

Kise reiterated the defense's claim that Trump did not commit fraud and that there were no victims of his alleged conduct.

"The attorney general has no case," Kise said.

Prosecutors intend to prove in the coming months that "each defendant engaged in repeated, persistent, illegal acts in conduct of business," according to the opening statement from Kevin Wallace of the attorney general's office.

Referring to Judge Engoron's partial summary judgment last week, Wallace said that "the people have already proven" that former President Trump used "false, misleading" statements that were "repeatedly [and] persistently used in the conduct of business."

But prosecutors will further demonstrate that Trump and his co-defendants knew those statements were false and continued to peddle them anyway in furtherance of their alleged scheme, Wallace told the judge.

"The defendants were lying year after year," he said.

Wallace played clips of video depositions to punctuate his remarks, including testimony from Trump himself, as well as Eric Trump and former Trump attorney Michael Cohen -- whose congressional testimony years ago precipitated the state's investigation and some of the key allegations underpinning their case.

"The goal was to use each of [Trump's] assets and increase its value in order to get to the end result number," Cohen said during his taped deposition. "It was essentially backing in numbers to each of the asset classes in order to attain the number that President Trump wanted."

Trump and his co-defendants "knew that a high net worth was necessary to get and maintain certain financial benefits," Wallace said, pointing to basic principles of accounting and finance.

Throughout Wallace's remarks, the attorney general's office flashed graphics on television screens inside the courtroom showing some of the alleged inflated values of Trump's properties alongside the amounts the properties were appraised at.

Seated in his chair with his arms crossed, Trump visibly shook his head at times during the prosecutor's opening statement. At one point he seemed to mutter something under his breath.

The former president whispered with his attorneys throughout.

Former President Trump has confirmed he plans to testify as a defense witness on Monday.

"I will be testifying on Monday," Trump wrote on his social media platform.

Court is not in session today, but Trump is expected to be in attendance tomorrow.

Trump's plan to testify was thrown into question on Tuesday after Judge Arthur Engoron denied a request from the defense to delay the testimony to accommodate Trump's effort to appeal the limited gag order in the case that prohibits him from commenting on the judge's staff.

"He is not capable of fully testifying because he is subject to the gag order," Kise said, arguing for a delay.

"Absolutely not. No way, no how. It's a nonstarter," Engoron said in response to the defense's request for a delay. "If he is going to testify, it'll be Monday, and that's that."

While Trump's lawyers have attempted to appeal the limited gag order to a higher court, their application to expedite the appeal was denied on Monday, ensuring that the limited gag order will be in place when Trump testifies.

During a campaign stop in Iowa, Trump repeated his claims that his opponents are trying to silence him, describing the gag order as an "honor."

"In many ways, it's an honor because if they wanted to hear me speak, they wouldn't do the gag order," Trump said.

When asked if he's concerned about his scheduled court testimony, Trump said "No, not at all."

Trump is set to be the final witness for the defense case when he testifies on Monday.

ABC News' Soorin Kim and Lalee Ibssa contributed to this report.