Most employers asking this question are already in trouble. The FMLA does not make someone unfireable — but it creates a legal presumption that any adverse action taken close to protected leave was caused by that leave. Overcoming it requires documentation that existed before the leave began, consistent treatment of similarly situated employees, and managers who know what not to say. This post covers what the law actually prohibits, when termination is defensible, and the specific patterns that can get companies sued.