Anti-free speech demonstrators at one of America’s most vaunted universities have claimed a pair of scalps – a husband-wife duo who say teaching is too much trouble in a campus climate “not conducive to civil dialogue.”

Yale University professors Nicholas and Erika Christakis, who both have always gotten overwhelmingly positive reviews from students, said they have had enough, after an email she sent sparked a campus-wide controversy that soon pulled him in.

“I have great respect and affection for my students, but I worry that the current climate at Yale is not, in my view, conducive to the civil dialogue and open inquiry required to solve our urgent societal problems,” she said in an email to The Washington Post.

“I have great respect and affection for my students, but I worry that the current climate at Yale is not, in my view, conducive to the civil dialogue and open inquiry required to solve our urgent societal problems.”

- Erika Christakis, Yale professor

The affair began in October, when Erika Christakis, a psychology professor and associate master at the school’s Silliman College, one of a dozen residential communities, sent out an email defending the right of students to wear costumes which may be “culturally appropriating.” That spurred outrage and led to one student confronting Nicholas Christakis on the campus quad and berating him in a shocking episode that was caught on video that soon went viral.

The video showed Nicholas Christakis, a physician and professor of social and natural science, calmly trying to reason with a student who was screaming at him for not keeping students “safe,” as others snapped their fingers in a trendy sign of approval.

Erika Christakis said she will quit teaching indefinitely and cited a campus atmosphere not “conducive to the civil dialogue and open inquiry required to solve our urgent societal problems.” Her husband said he would not teach scheduled classes in the spring, and would take a sabbatical.

Neither Yale officials nor the Christakises responded to requests for comment.

“I don’t have much to add to her decision,” Yale Dean Jonathan Holloway told The Washington Post, adding that as a lecturer, Christakis is paid per course and can decide whether to teach each semester.

The school is ultimately responsible for the chill on free speech, according to Foundation for Individual Rights in Education.

"While Yale did eventually get around to issuing a statement in favor of free expression, it’s hard to imagine that Erika or Nicholas Christakis would have decided to quit teaching at Yale and take a sabbatical, respectively, had Dean Holloway or President [Peter] Salovey consistently shown their support for free expression through their words and actions on campus," said FIRE's Robert Shibley.

The issue of free expression on campus has come into sharp relief on several campuses, with students calling for “safe zones” and speech codes where words and deeds deemed offensive are barred. Erika Christakis provoked outrage when she sent an email to Silliman residents questioning the desire to find offense in Halloween costumes.

“Is there no room anymore for a child or young person to be a little bit obnoxious… a little bit inappropriate or provocative or, yes, offensive?” Christakis wrote. “American universities were once a safe space not only for maturation but also for a certain regressive, or even transgressive, experience; increasingly, it seems, they have become places of censure and prohibition.”

He husband later apologized for his role in the controversy in a heartfelt mea culpa delivered in his own home.

“I have disappointed you and I’m really sorry,” he told about 100 students gathered in his living room last month, as Holloway and other university administrators stood by.

“I’ve spent my life taking care of these issues of injustice, of poverty, of racism,” he said. “I have the same beliefs that you do … I’m genuinely sorry, and to have disappointed you. I’ve disappointed myself.”

In a related matter, Yale announced it could soon follow Harvard and Princeton and change the administrative title both Nicholas and Erika Christakis hold, as "master" evokes imagery associated with slavery. 

“The word ‘master’ can evoke thoughts of slavery and other forms of subjugation, and it has made me at times quite uncomfortable to be referred to as ‘master,’” Nicholas Christakis said in a letter to students at the beginning of the year.