Federal agents often wear "Police" because that is the most well recognized word to indicate law enforcement - and works in multiple languages. The point is to

Federal agents often wear "Police" because that is the most well recognized word to indicate law enforcement - and works in multiple languages. The point is to ensure that arrestees know they are law enforcement. There is no legal requirement to indicate they are police, let alone the specific department they are in. An undercover officer can arrest someone without any badge or marking at all. > an FBI agent is not allowed to identify as a police officer? I don't know what gave you that impression. They are law enforcement officers with the jurisdiction to arrest anywhere in the US.