The categories of life was a system used to classify people on Earth when, after Miracle Day, people stopped dying. Badly injured people, Categories 1 and 2, were taken to overflow camps. Those in Category 1 were secretly taken to modules and burned alive. This seemed the only way humans could die after the Miracle occurred. Even after the Modules became common knowledge, they were still used. Governments gave law enforcement special powers to search premises without a warrant if there was suspicion of an unlicenced Category 1 located there.