Causation, Part 8 (Price Waterhouse)

In the last post, I discussed the first part of the Price Waterhouse plurality opinion. That part of the opinion did some important work. It noted Congress’ rejection of sole causation. It recognized that the Court needed to make a choice among possible causal standards. It explained “but for” cause and its inherent limits, both theoretical and practical. This portion of the opinion laid the groundwork for a portion of the plurality’s conclusion: that an employee may prevail on a discrimination claim by showing that a motivating factor played a role in an employment outcome.

In this second portion, the plurality tried to balance the interests of employers and employees. With very little explicit reasoning related to Title VII, the Court declared that the balancing of these interests required the Court to create an affirmative defense to liability. It borrowed the contours of this affirmative defense from First Amendment constitutional law and a decision under the National Labor Relations Act.

If an employee shows that a protected trait played a motivating factor in an employment decision, the employee wins the case unless the employer can establish an affirmative defense. The affirmative defense requires the employer to show that it would have made the same employment decision, even if it had not taken the protected trait into account. If the employer establishes the affirmative defense, it faces no liability under Title VII. The Court noted if an employer allowed a protected trait to infect its decisionmaking process, then the employer should bear the risk that the “influence of legal and illegal motives cannot be separated.” 490 U.S. 228, 250 (1989).

The plurality recognized that the idea of causation has at least two distinct components. The first part is the choice of substantive causal standard, whether that standard is sole cause, “but for” cause, motivating factor, or some other causal standard. The second part involves allocating burdens for establishing cause. Price Waterhouse explicitly recognized that there is nothing inherent in the notion of causation that requires the plaintiff to bear the entire causal burden.


As we will explore in upcoming posts, Congress amended Title VII in 1991 in response to Price Waterhouse. Congress rejected the idea that an employer should escape liability if it established the affirmative defense. Instead, proving the affirmative defense entitles the employer to a partial defense to certain damages.

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