Most California employers hear "at-will" and assume it means they can fire anyone, anytime, for any reason, without consequence. That belief causes more lawsuits than almost any other misunderstanding in employment law. The short answer: at-will employment protects you from claims that you needed "good cause" to terminate someone, but it does nothing to shield you from claims that the termination was illegal for some other reason. Knowing exactly where that line sits is the d