Under previous Supreme Court decisions, plaintiffs claiming racial or sexual harassment faced a lower burden to prove an employer liable when the harassment was committed by a supervisor rather than a co-worker. For instance, if the harassing supervisor was found to have taken adverse actions against an employee, like demoting the person, the employer was strictly liable for that action. And even when a supervisor’s harassment did not culminate in a specific negative employment action, the employer could be held liable if the employer failed to prove that it exercised reasonable care to prevent and correct any harassing behavior.

But for an employer to be held liable when a co-worker is accused of harassment, the plaintiff has the burden of proving that the employer was negligent by not stopping the behavior.

The court upheld a decision by the Seventh Circuit Court of Appeals that held that Ms. Davis was not a supervisor and that Ball State was not negligent with respect to her behavior. Justice Alito emphasized that the court’s adoption of a narrower definition of supervisor did not leave plaintiffs unprotected, but left them with a different burden of proof.

In a stinging dissent, Justice Ruth Bader Ginsburg argued that the majority opinion “is blind to the realities of the workplace.” She wrote that it is not easy for an employee to tell a harassing supervisor to “buzz off” even when the supervisor does not have the power to fire or demote.

“An employee who confronts her harassing supervisor risks, for example, receiving an undesirable or unsafe work assignment or an unwanted transfer,” Justice Ginsburg wrote. “She may be saddled with an excessive workload” or a shift that disrupts her family life.