Prior posts catalogued the Court’s faulty reasoning in Gross. The Court relied on a contorted history of the relationship between Title VII, Price Waterhouse, the ADEA, and the 1991 amendments to Title VII. The Court improperly defaulted to tort law to define causation. It then oversimplified the tort common law by failing to recognize that tort law allows for alternate ways to prove causation and allows for the burden of proof on causation to shift to defendants.
In his dissent in Gross, Justice Breyer discussed an additional problem. Tort cause largely developed in the context of physical events. Indeed, the quintessential negligence example is that of a car accident. Causation analysis that works for car accidents probably does not work well in cases where cause might be a mental state. As Justice Breyer explained:
It is one thing to require a typical tort plaintiff to show “but-for” causation. In that context, reasonably objective scientific or commonsense theories of physical causation make the concept of “but-for” causation comparatively easy to understand and relatively easy to apply. But it is an entirely different matter to determine a “but-for” relation when we consider, not physical forces, but the mind-related characterizations that constitute motive. Sometimes we speak of determining or discovering motives, but more often we ascribe motives, after an event, to an individual in light of the individual’s thoughts and other circumstances present at the time of decision. In a case where we characterize an employer’s actions as having been taken out of multiple motives, say, both because the employee was old and because he wore loud clothing, to apply “but-for” causation is to engage in a hypothetical inquiry about what would have happened if the employer’s thoughts and other circumstances had been different. The answer to this hypothetical inquiry will often be far from obvious, and, since the employee likely knows less than does the employer about what the employer was thinking at the time, the employer will often be in a stronger position than the employee to provide the answer.
All that a plaintiff can know for certain in such a context is that the forbidden motive did play a role in the employer’s decision. . . .
But the law need not automatically assess liability in these circumstances. In Price Waterhouse, the plurality recognized an affirmative defense where the defendant could show that the employee would have been dismissed regardless. The law permits the employer this defense, not because the forbidden motive, age, had no role in the actual decision, but because the employer can show that he would have dismissed the employee anyway in the hypothetical circumstance in which his age-related motive was absent. And it makes sense that this would be an affirmative defense, rather than part of the showing of a violation, precisely because the defendant is in a better position than the plaintiff to establish how he would have acted in this hypothetical situation.
Gross v. FBL Fin. Servs., Inc., 557 U.S. 167, 190-92 (2009).