(Reuters) – There is a curious disconnect between what the presumptive Republican presidential nominee Donald Trump says in public about the judge overseeing two class actions claiming Trump University was a swindle and what Trump’s lawyers do in court.

The candidate, as you know, has suggested that U.S. District Judge Gonzalo Curiel of San Diego is biased against him because Curiel – an Indiana native whose parents were immigrants from Mexico – disapproves of Trump’s immigration policies. Despite criticism of his comments from luminaries in his own party, Trump has refused to back down, calling the judge’s heritage “an absolute conflict” in an interview last week with the Wall Street Journal.

But in court, where the Trump University litigation has been plodding along since 2010, there has been nary a suggestion that Judge Curiel should be removed from the case – not for his Mexican roots or for any other reason. And no matter what Trump says, his defense lawyers at O’Melveny & Myers are exceedingly unlikely to file a motion asking the judge to step aside, or recuse himself, based on what we know today.

In fact, if O’Melveny were to file a recusal motion, according to two law professors and three private lawyers specializing in legal ethics, Trump’s lawyers would expose themselves to sanctions under the Federal Rules of Civil Procedure and to discipline by state bar associations.

As many, many legal experts have opined in the past few days, a federal judge’s ethnicity or national origin cannot serve as the basis for a claim of judicial bias. The 2nd U.S. Circuit Court of Appeals, for instance, held in its 1998 opinion in MacDraw Inc v. CIT Group that U.S. District Judge Denny Chin (now on the appeals court) was within his rights to sanction two lawyers who asked whether his Asian ancestry prejudiced him against them. (They were involved in completely separate litigation against an Asian fundraiser for President Bill Clinton, who appointed Chin.) “Courts have repeatedly held that matters such as race or ethnicity are improper bases for challenging a judge’s impartiality,” the 2nd Circuit said. Added Alexandra Lahav, who specializes in legal ethics at the University of Connecticut: “There is no basis in the law or our legal history. It’s antithetical to the rule of law.”

Trump has a First Amendment right to express his opinion of the Trump University proceedings, which have certainly not gone the way he and his lawyers would have liked. Judge Curiel has certified two class actions, one against Trump himself, by consumers who claim the real estate seminars were nothing but a high-pressure sales scheme. Plaintiffs’ lawyers at Robbins Geller Rudman & Dowd have even persuaded the judge to allow them to pursue a racketeering claim, which carries treble damages, against Trump. Most recently, the judge unsealed a trove of documents revealing the sales secrets of the now-shuttered Trump University operation, as well as testimony in which some former students and instructors described the program as a fraud. (Trump maintains that the vast majority of those who attended the seminars were satisfied with the program and that critics were simply disgruntled former employees.)

Outside of court, Trump can say just about whatever he wants about the case without much risk of being held accountable. It might be another story if the candidate were to express contempt for Judge Curiel or the proceeding inside the judge’s courtroom, but so far, Trump has not made accusations to Curiel’s face.

Nor are the candidate’s lawyers responsible in court for what their client says about the judge outside of the courtroom. The American Bar Association’s model rules of professional conduct explicitly say that representing a client does not mean a lawyer endorses the client’s “political, economic, social or moral views or activities.” Ethics adviser Thomas Mason of Harris Wiltshire & Grannis said lawyers generally do not face sanctions for what their clients say – and that goes double when the client is running for president. “How easy do you think it would be for any lawyer at any firm to control what Mr. Trump says?” Mason asked.

If, however, O’Melveny were to accuse Judge Curiel of bias in a filing that cited only his heritage as evidence, according to legal ethics experts, the firm could be accused of bringing a frivolous motion, according to Mark Foster of Zuckerman Spaeder and Barry Cohen of Crowell & Moring, who counsel law firms on professional responsibility. The rules for civil suits in federal courts prohibit lawyers from filing motions they know to be without merit – and legal experts say O’Melveny ought to know they cannot ask for Judge Curiel to recuse himself simply because of his Mexican roots. (Typically, recusal motions in federal court cite a judge’s financial interest in the outcome of the case or the involvement of a friend or family member of the judge.)

“There won’t be a recusal motion,” said Stephen Gillers, a law professor at New York University. “The repercussions of a motion based on the judge’s Mexican heritage would be too harsh. No law firm would do that.”

Gillers said Trump may already have waived the right to demand Curiel’s recusal by waiting to raise the issue until the judge issued rulings he does not like. According to both Gillers and law professor Lahav, Trump cannot claim Judge Curiel was biased against him on appeal if Trump lawyers do not ask the judge to step aside while the case is still in the lower court.

So how should Judge Curiel handle Trump’s criticism? The judge is not permitted to comment publicly on cases under way in his court, except from the bench or in rulings. (In his order unsealing documents, for instance, Judge Curiel mentioned Trump’s frontrunner status and said the defendant “has placed the integrity of these court proceedings at issue.”) The legal experts I spoke with said his likeliest (and smartest) course is to say nothing to Trump’s lawyers about their client’s out-of-court statements unless he is called upon to rule on a recusal motion.

Which he won’t be.

A spokeswoman for O’Melveny declined to comment. I sent plaintiffs’ lawyer Jason Forge of Robbins Geller an email asking whether he would bring a sanctions motion if Trump’s lawyers asked for recusal; in an email response, he declined to comment.

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