People in jails and prisons retain constitutional rights, and they lose most of their cases anyway — usually on a procedural rule that has nothing to do with what happened to them. This article explains how prisoner rights litigation actually works, beginning with the grievance process that must be completed perfectly before a court will hear anything. It walks through the Eighth Amendment standards for force, medical care, and conditions, and the different rules that apply to pretrial detainees who have been convicted of nothing. It covers religious exercise, mail and communication, access to courts, disability accommodation, and retaliation. It explains the Prison Litigation Reform Act in operational detail, including the physical injury requirement, the three-strikes rule, and the limits on injunctive relief. It closes with what actually works: contemporaneous documentation, perfect exhaustion, and the medical record.