[rachofsunshine]

Also NAL but I don't think you're correct about this.

First: the standard isn't relevant to a nuisance suit, since by definition you don't expect to win a nuisance suit anyway.

But setting that aside, disparate impact requires a significant difference in outcome and can be defended against by showing that the standards are relevant to job performance ("business necessity"). That's true for both the federal Civil Rights Act and the California Equal Pay Act (which is what this suit was brought under). So a "single variable analysis" isn't the end of the story, and employers can (and often do) provide statistical arguments that their policies satisfy business necessity.

I'd suggest looking up the case (Griggs v. Duke Power Co.) that established the disparate impact standard in the first place. TLDR, a company that had explicitly discriminatory Jim Crow-era policies banning black employees from certain departments adopted new requirements on the day the Civil Rights Act went into effect. Those requirements hadn't been in place before, Duke Power could not show any actual connection with job performance, and white employees were two to ten times more likely to satisfy them. A unanimous court (which, as a fun trivia fact, included an open former member of the Klan!) said nope, can't do that.