It holds retaliation claims to a stricter standard of proof than other forms of discrimination claims.
In the underlying action, the University of Texas Southwestern Medical Center wanted a discrimination lawsuit won by Dr. Naiel Nassar thrown out. Nassar, after complaining of harassment, left in 2006 for another job at Parkland Hospital, but the hospital withdrew its job offer after one of his former medical center supervisors opposed it. Nassar sued, saying the medical center retaliated against him for his discrimination complaints by encouraging Parkland to take away his job offer. A jury awarded him more than $3 million in damages.
The medical center appealed, saying the judge told the jury it only had to find that retaliation was a motivating factor in the supervisor's actions, called mixed-motive. Instead, it said, the judge should have told the jury it had to find that discriminatory action wouldn't have happened "but-for" the supervisor's desire to retaliate for liability to attach.
Justice Anthony Kennedy, who wrote the opinion, agreed with the lower court and the university, saying that an employee "must establish that his or her protected activity was a but-for cause of the alleged adverse action by the employer." But he didn't rule completely for the medical center, sending the case back to the lower courts after saying a decision on the resolution of the case "is better suited by courts closer to the facts of this case."