University of Tex. Southwestern Med. Ctr. v. Nassar (opinion here) is the Supreme Court opinion setting forth the "causation" standards that apply to retaliation cases under Title VII of the Civil Rights Act of 1964.
Nassar was a doctor and professor at Univ. of Texas. He also worked at the University's medical center. He complained of harassment and discrimination by Dr. Levine. He tried to work only at the hospital to avoid Dr. Levine's harassment at the University. But the University blocked his effort, claiming that University policy required attending doctors also to be professors at the medical school.
So, Nassar sued for retaliation, claiming discrimination / constructive discharge, and retaliation in that the University blocked his hiring at the hospital. After Nassar won a verdict, the Supreme Court accepted review to determine whether the retaliation claim was decided under the correct "causation" framework.
The Court decided that in Title VII cases, the causation standard is "but for," which means that the employer would not have taken negative action against the employee "but for" the employee's engaging in protected activity. Put another way, the harm would not have occurred if the employee had not complained.
Along the way, the Supreme Court majority explained the causation standard that applies to Title VII discrimination cases. This is known as the "motivating factor" standard:
An employee who alleges status-based discrimination under Title VII need not show that the causal link between injury and wrong is so close that the injury would not have occurred but for the act. So-called but-for causation is not the test. It suffices instead to show that the motive to discriminate was one of the employer’s motives, even if the employer also had other, lawful motives that were causative in the employer’s decision. This principle is the result of an earlier case from this Court, Price Waterhouse v. Hopkins, 490 U. S. 228 (1989), and an ensuing statutory amendment by Congress that codified in part and abrogated in part the holding in Price Waterhouse, see §§2000e–2(m), 2000e–5(g)(2)(B).
Why the separate standards, you ask? Because in Title VII, the discrimination provisions are covered by a specific statute, and that statute was amended to include the motivating reason standard. The anti-retaliation section is in another part of Title VII. So, what the Court really decided was that the 1991 amendment to Title VII's causation provision did not apply to the retaliation piece.
It remains to be seen whether this decision will influence California courts' interpretation of the causation standard. Earlier this year, the California Supreme Court examined causation standards in "mixed motive" cases (discussed here). We will see what the lower courts do with Nassar in the coming months.
DGV
