Donald Trump and his co-defendants have filed a motion seeking a mistrial on the grounds that the trial has been "tainted" by the appearance of bias on the part of Judge Arthur Engoron and his law.

"This appearance of bias threatens both Defendants' rights and the integrity of the judiciary as an institution," Trump's attorneys say in the filing. "As developed herein, in this case the evidence of apparent and actual bias is tangible and overwhelming."

"Specifically, the Court’s own conduct, coupled with the Principal Law Clerk, Allison Greenfield’s unprecedented role in the trial and extensive, public partisan activities, would cause even a casual observer to question the Court’s partiality," they write.

"Such evidence, coupled with an unprecedented departure from standard judicial procedure, has tainted these proceedings and a mistrial is warranted," the filing says.

Donald Trump's lawyers are scheduled to resume their direct examination of expert witness Jason Flemmons this morning, continuing a line of questioning yesterday that largely placed responsibility for Trump's financial statements on Trump's external accountants.

Flemmons, who was qualified as an expert on accounting, explicitly criticized the testimony of Donald Bender, Trump's accountant at Mazars USA who was the New York attorney general's first witness, disputing Bender's claim that he would have wanted to see any appraisals that the Trump Organization conducted.

Flemmons also testified that Trump's financial statements should have sent a "buyer beware" signal to lenders due to the "highly cautionary language" in their disclaimer, which allowed Trump to make claims that significantly departed from generally accepted accounting principles.

To the extent that the statements and the Trump Organization's representations about the statements were inaccurate, Flemmons placed responsibility on Bender and his colleagues at Mazars, rather than the Trump Organization.

Expert witness Jason Flemmons cast doubt on the testimony of the Trump Organization's former external accountant Donald Bender, who said he would have wanted to review any appraisals that the Trump Organization conducted.

"That's not something that is required by professional standards," said Flemmons, testifying for the defense. "His testimony was not professionally plausible."

That prompted a strong objection from state attorney Kevin Wallace.

"Is he trying to say the witness is lying?" Wallace said.

"Not to put too fine a point on it," Judge Engoron quipped.

Asked to confirm what he meant by "professional plausible," Flemmons said it would be "highly unusual" for Bender to request appraisals outside what was mentioned in the statement of financial condition.

"Accountants in the industry do not go seeking records for things that are not in the four corners of the statement of financial condition," Flemmons said.

Court was subsequently adjourned for the day, with Flemmons scheduled to continue his testimony tomorrow.

Defense expert Jason Flemmons described the disclaimer included in Donald Trump's financial statement as the "highest level disclaimer" that could have been provided to bankers reviewing the document.

Flemmons said that the disclaimer, which he said includes "highly cautionary language," would allow a user to make claims that significantly departed from generally accepted accounting principles, known in the industry as GAAP.

"Was that language present in a substantially similar form in the compilation statements issued by Mazars for Donald Trump?" defense attorney Jesus Suarez asked.

"Yes," Flemmons said, adding that the disclaimer was "effectively saying 'user beware.'"

During his testimony and in statements to the media, Trump has claimed that the disclaimer shields him from liability in the case.

Suarez also used Flemmons' testimony to suggest that Trump's external accountants were responsible for understanding the methods used in the financial statement and determining their appropriateness.

That appeared to conflict with testimony of former Trump accountant Donald Bender of Mazars USA, who described his role as akin to plugging numbers provided by the Trump Organization into a template.

Cushman & Wakefield executive David McArdle, who was hired to appraise the value of 71 undeveloped residential units at the Trump National Golf Club in Westchester County, New York, testified that he also conducted multiple appraisals for conservation easements at the property in 2014 and 2015.

Signing a conservation easement would allow the Trump Organization to give up their development rights and treat the difference in property value as a charitable donation, according to the New York attorney general.

By giving up the right to develop the 71 residential units, McArdle found that the donation was worth $43 million, according to an April 2014 appraisal. A later appraisal McArdle conducted in 2015 landed on a similar valuation of $45.2 million.

But Trump's financial statements from those years appear to ignore the appraisals, valuing the land from the undeveloped units at $101 million, according to documents entered into evidence.

"Based on the supporting data, the only source for the increase in the number of units and profit per unit were telephone conversations with Eric Trump," the New York attorney general alleged in her complaint.

McArdle also testified that he was consulted to appraise Seven Springs, a New York estate Trump purchased for $7.5 million in 1995.

To value the property, which could be subdivided into 24 to 26 residential lots, McArdle testified that he toured the site, consulted a local expert, and spoke with Eric Trump on multiple occasions.

"He had a very high opinion of the property, which didn't surprise me," McArdle said.

His appraisal ultimately determined the total value for the lots in 2014 was $30-$50 million, McArdle said.

But the New York attorney general alleges that appraisal was ignored in Trump's 2014 financial statement, in favor of a "false and misleading" value of $161 million for a portion of the undeveloped lots.