When someone becomes a police officer they may want to move up the ranks or be promoted to higher levels within the police department. However, first they must become a police officer. Usually captains and other high ranking officials within the police department don’t get their jobs without being an entry level police officer first. They must serve their time working as a police officer in order to understand every aspect of law enforcement.
Once they have done that for several years they have gained the experience that they need to move up or be promoted to a higher level. To become a captain in a police department a police officer would have to have an impeccable record.