Undercover Agents. Traditionally, law enforcement organizations and private detectives have used covert operations; these individuals are known as undercover agents.
Agents working undercover may commit crimes to further their investigations. This issue is described by Joh using the phrase "sanctioned criminality," which she limits primarily to undercover law enforcement officials while excluding confidential informants.
These illegal actions serve primarily to keep or strengthen the suspect's cover identity and "offer opportunities for the suspect to engage in the target crime." To further the inquiry, these offenses must be required; otherwise, they risk being charged as regular crimes.
Impersonators. Police impersonation is the practice of pretending to be a police officer in order to deceive.
Impersonating police has a long history. In order to demand bribes or conduct sex crimes, impostors pretended to be constables, marshals, or sheriffs' officers in 17th- and 18th-century London.
The amount of study on police impersonation is small. According to some academics, police impersonation may reduce public trust in authorities and law enforcement, "especially if victims feel that the incident was a [legal] police action carried out by a corrupt cop."