A dashboard camera caught a confrontation between a New Jersey state trooper and plainclothes Bergen County police officers on the NJ Turnpike back in May. In video obtained by CliffviewPilot.com, a state trooper stopped and approached a minivan with its lights on that had pulled over another vehicle.
My Fox NY reports that the state trooper was concerned that the plain clothed officers could have been suspects involved in recent robberies who impersonated police. The state trooper approached the minivan with his gun unholstered and was met by the Bergen County officers, which began a profanity laced tirade.
Things only escalated when a Bergen County police sergeant arrived. The Bergen County Police Chief, Brian Higgins said (via My Fox NY) that "neither the trooper or the officers were at fault... they were all doing their jobs." However, My Fox NY reports that the plainclothes Bergen County officers were reportedly disciplined. NJ state police have jurisdiction on state highways so it's uncertain why the Bergen County officers had pulled over the other driver.
WARNING: NSFW (Strong Language)