500
The court ruling that said if the plaintiff showed that discrimination played a "motivating part" in an employment decision, the employer can avoid liability only by proving by a preponderance of the evidence that it would not have made the same decision in the absence of the discriminatory motive. Basically proving that the hiring or firing of a person was solely determined by work performance and no other reason like gender, race, etc.
What is Price Waterhouse v. Hopkins (1989)