In the geographical area occupied by the US at least, being a cop is an action that a person takes. And a person has to continuously take actions to remain a cop. An individual does not wake up one day as a cop either through government dictate or other forms of magic. In order to become a cop a person has to voluntarily go to a government building, express a desire to join a group of people, and fill out some forms. In order to stay a cop, a person has to put on a uniform, wear a badge, show up to certain places at certain times, and self-identify as a cop.