Before today's first witness entered court, Trump attorney Chris Kise asked Judge Engoron to postpone today's proceedings after five members of the New York attorney general's team tested positive for COVID-19.

Describing the attorney general's conduct as "beyond irresponsible," Kise said that his team did not get adequate notice about the COVID exposures despite having close contact with positive individuals.

"Nothing else matters except for pursuing President Trump," Kise said. "We have the leading candidate for president of the United States in the courtroom today."

"The attorney general's office knew on Wednesday and didn't tell any of us," defense attorney Clifford Robert said. "We are truly in an outbreak."

Engoron declined to grant their requested delay.

In a statement, a spokesperson for New York Attorney General Letitia James said the state has complied with all CDC guidelines.

"Our office properly notified the court and defendants' counsel, and the court decided to proceed with trial today. If there were any concerns, defendants could wear masks today or at any point, but they have opted not to," the spokesperson said.

Trump called his former lawyer Michael Cohen a "proven liar" and "felon" as Trump entered the courtroom for his civil trial this morning.

"He's a felon, served a lot of time for lying, and we're just going to go in and see and I think you'll see that for yourself," Trump told reporters outside court.

Cohen pleaded guilty in 2018 to two separate criminal cases and eventually spent more than 13 months in prison -- but said that it was Trump who caused him to "follow a path of darkness."

-ABC News' Ricardo Montero contributed to this report.

Exiting his New York City apartment this morning, Michael Cohen told reporters he was "looking forward" to seeing Trump in court.

"It's been five years since we've been in the same room," Cohen said.

Cohen preemptively defended the credibility of his testimony and reiterated that he previously perjured himself "concert with and for the benefit of Donald J. Trump."

"My credibility should not be in question," Cohen said.

-ABC News' Eric Avram contributed to this report.

Donald Trump has arrived in court for the anticipated testimony of his former lawyer Michael Cohen.

New York Attorney General Letitia James is also attending the trial this morning.

James took her usual seat at the front of the courtroom's gallery, directly behind her team of lawyers at the counsel table.

The courtroom itself is nearly at capacity, with attendance matching the number of observers during the trial's opening statements.

The New York attorney general's civil fraud complaint against former President Trump lacks merit, a defense expert in accounting testified.

"My main finding is that there is no evidence whatsoever for any accounting fraud," New York University professor Eli Bartov said. "My analysis shows the statements of financial condition for all the years were not materially misstated."

Bartov's testimony bolstered the defense's contention that non-audited financial statements, like Trump's, are unreliable and represent only a first step in analysis.

"You cannot use the raw numbers in the statements as the basis for making decisions," Bartov said. "If you do that, you are likely to reach the wrong decision."

Judge Engoron asked Bartov whether the attorney general's complaint had no merit.

"This is absolutely my opinion," Bartov replied.

"And why is that?" defense attorney Jesus Suarez jumped in to ask.

"There is not a single reference to a specific provision of GAAP that was violated," Bartov said, referring to the generally accepted accounting principles." "If you allege there was an accounting violation, they have to tell us what provision was violated."

State attorneys objected to the relevance of Bartov's opinion, but Judge Engoron denied the objection.