The Family and Medical Leave Act looks like a simple entitlement — twelve weeks, unpaid, job protected — and produces a startling volume of litigation, almost all of it about administration rather than entitlement. This article explains why. It works through coverage and eligibility, the definition of a serious health condition that turns on treatment patterns rather than diagnosis, the notice obligations that run in both directions on five-business-day clocks, and the medical certification process where most employers lose: who may contact the provider, what may be asked, when a second opinion is available, and how recertification works. It then separates the two causes of action that FMLA plaintiffs plead, interference and retaliation, and shows why the interference claim is the dangerous one because intent is largely irrelevant. It covers intermittent leave abuse and the honest-belief defense, job restoration and the narrow key-employee exception, benefits continuation, the damages structure including liquidated damages, individual supervisor liability, and the interaction with the ADA, workers' compensation, the PWFA, and state paid family leave. A worked example follows a fictional employer through a mishandled intermittent leave request.