John Yoo. (Photo: Diego Radzinschi)

The most protested professor in the legal academy is back in the spotlight—this time for comments the conservative academic made last month on the Fox News show hosted by Laura Ingraham that linked impeachment witness Lt. Col. Alexander Vindman to espionage.

It's just the latest dustup involving longtime University of California, Berkeley School of Law professor John Yoo, who is best known as the author of the controversial so-called "torture memos" from 2002, which argued that interrogation techniques such as waterboarding and sleep deprivation are legal amid the War of Terror.

Vindman's attorney, David Pressman of Boies Schiller Flexner, on Wednesday issued a letter to Fox News demanding a retraction or correction clarifying that his client never engaged in espionage on behalf of the Ukrainian government. Vindman and his family were put under security by the Army as a safety precaution following his Capitol Hill testimony on Nov. 19.

The spat has generated widespread media coverage, despite Yoo's attempts to walk back the espionage claim in a subsequent USA Today op-ed. (Yoo did not respond to requests for comment Thursday but has written that he doesn't believe Vindman is a spy for the Ukrainians.)

Yoo is no shrinking violet and often comments in the media on matters pertaining to national security and other topics. However, he has generally kept a lower profile in the decade since Berkeley students unsuccessfully pushed to have him fired from his teaching post for authoring the torture memos as a Justice Department lawyer during the administration of President George W. Bush.

The backlash from students, alumni and others reached a fever pitch in 2008, prompting then-dean Christopher Edley Jr. to issue a statement that to fire or sanction Yoo for his government work and legal views would be a violation of his academic freedom, even though he disagrees strongly with Yoo's legal conclusions regarding torture. Yoo's dismissal would only be justified in the event of clear professional misconduct or a criminal act, Edley wrote.

"Absent very substantial evidence on these questions, no university worthy of distinction should even contemplate dismissing a faculty member. That standard has not been met," reads Edley's 2008 statement.

Not everyone was convinced, however. About 50 people dressed in orange prison jumpsuits protested Yoo during the law school's 2008 graduation ceremony and protesters occasionally show up at his speaking engagements. The law school came under criticism in 2010 for not disclosing the location of Yoo's class on the California Constitution, which was widely viewed as an attempt to thwart protesters.

Edley said in an interview Thursday that he stands by his handling of the calls for Yoo's dismissal, and that part of job law dean is to maintain the diversity of ideas on campus.

"The most important test is whether the individual is a good teacher and scholar, and in John Yoo's case, the answer to both is a resounding yes," Edley said.

Current Berkeley Law Dean Erwin Chemerinsky was not immediately available Thursday for comment on Yoo's latest controversy over Vindman. Chemerinsky is a free speech expert and frequently defends the rights of faculty and others to engage in campus speech without reprisal.

But Chemerinsky had strong words for Yoo before becoming dean at Berkeley in 2017. He told The Nation in 2014, as dean of the University of California Irvine School of Law, that Yoo should be prosecuted for his role in the torture of detainees in the War of Terror. As the author of the memos that authorized such practices in violation of The Federal Torture Act he should be held to account, according to Chemerinsky.

"All who planned, all who implemented, all who carried out the torture should be criminally prosecuted," Chemerinsky told The Nation. "How else do we as a society express our outrage? How else do we deter it in the future—except by criminal prosecutions?"

Yoo has defended the torture memos on the grounds that he believed methods such as waterboarding could help the CIA prevent additional Al Qaeda attacks in the wake of 9/11.

Yoo joined the Berkeley Law faculty in 1993 after clerking for U.S. Supreme Court Justice Clarence Thomas and gained tenure in 1999. He took a leave of absence from the school early in the Bush Administration, where he worked in the Justice Department's Office of Legal Counsel before returning to the law school in 2004.

Pressman, Vindman's attorney, did not respond to requests for comment Thursday on the Fox News matter. The dispute stems from Yoo's Oct. 28 appearance on the "Ingraham Angle" in which Yoo and Ingraham discussed Vindman's national security role.

"Here we have a U.S. national security official who is advising Ukraine, while working inside the White House, apparently against the president's interest, and usually, they spoke in English. Isn't that kind of an interesting angle on this story?" Ingraham said on air.

"I found that astounding," Mr. Yoo responded. "Some people might call that espionage."

A Fox News spokeswoman did not respond to requests for comment on the matter, but the network issued a statement to The New York Times saying, "as a guest on Fox News, John Yoo was responsible for his own sentiments, and he has subsequently done interviews to clarify what he meant."

Yoo's  Nov. 1 op-ed in USA Today states that he did not, in fact, accuse Vindman of espionage on air. Rather, Yoo wrote that he said the Ukrainians appear to have engaged in espionage in attempting to gather information from Vindman. Still, Yoo acknowledged in the op-ed that he had "really stepped in it," during his Fox News appearance.