Part of the fun of going back into the office means joking around with colleagues. But new research indicates workers may need to be more careful about what they quip about in the workplace.

The number of U.K. employment court cases concerning the use of “banter” in the workplace rose 45% in the last year, according to GQ Littler, a London-based employment law firm. And the number of employment tribunals—court cases in the U.K. involving employees and employers—related to ‘banter’ went from 67 in 2020 to 97 in 2021, according to the firm.

“‘Banter’ has increasingly been invoked in employment tribunals as a justification for alleged discrimination and harassment,” the firm wrote.

What one employee thinks is banter or light-hearted teasing can be construed as bullying or harassment by another in a court of law, according to the firm, particularly when the discriminatory comments are directed at someone's age, sex, nationality, and/or race.

This isn't just a problem for line managers and bosses. Companies can be found vicariously liable for comments made by staff in the course of employment, even if the comments deemed inappropriate were made outside working hours, according to the law firm.

“Humor in the workplace is important—it can help boost morale and reduce stress. However, employees should be wary of making jokes that stray into offensive territory,” said Lisa Rix, senior associate at GQ Littler. “But this doesn’t mean the end of workplace fun: It is possible to make jokes which don’t constitute harassment!”

Banter gone wrong

Workplace teasing has made headlines recently.

Last September, Ana Lacatus, a female Barclays employee, won an employment lawsuit against the bank after she said her line manager repeatedly referred to women as “birds.” After she suggested he not use that phrase, she says the line manager, James Kinghorn, continued to use the expression to make her feel uncomfortable. In the tribunal brought against Kinghorn; a second manager, Avneesh Singh; and Barclays, Kinghorn said he thought that she had recognized the jokes were “light-hearted banter.”

The court sided with Lacatus, concluding that Kinghorn's attempt to be ironic “used sexist language.” Barclays later released a statement after the ruling saying that said the language used by Kinghorn was “inappropriate and not acceptable.”

There are several other cases of derogatory references often made at the expense of characteristics protected under the U.K.'s Equality Act, according to GQ Littler. Beyond gender, these include discrimination in workplace against sexual orientation, relgion, race, disability, and age.

The firm notes that these cases could be avoided if companies institute “up-to-date and comprehensive policies on equality, diversity, and inclusion," adding employers should also keep an eye on their workplace culture to make sure it is professional and appropriate, as well as fun.

All in all, the law firm’s advice about workplace banter is simple: Treat others the way you want to be treated.

“People should think about how that joke would sound being repeated back to them and whether they would feel uncomfortable trying to justify the comments if questioned about them,” Rix said.