The U.S. Supreme Court had decided to let us know. It granted cert yesterday in Vance v. Ball State University. Vance, the only African-American in Ball State's catering department, claims that a co-worker who had the authority to direct her work slapped her, threatened her, and used racial epithets. The U.S. Supreme Court has held that an employer is vicariously liable when a supervisor creates a hostile work environment, but if the harasser is a co-employee, the plaintiff must prove employer negligence. Here's the cert petition (PDF).