A federal judge on Monday unsealed disturbing dashcam footage of a suburban Kansas City, Missouri police officer tasering a 17-year-old motorist who became brain damaged after what was billed as a routine traffic stop. That stop subsequently turned into an event of excessive force—resulting in a four-year prison sentence for Officer Timothy Runnels of the Independence Police Department.

The video shows Runnels tase and yank Bryce Masters out of the car and down on the street as Masters howls. The boy was filming the officer with his mobile phone, which the officer flings to the street. “Am I under arrest? Am I under arrest?” the teen is overheard saying before he is stunned and grabbed from the vehicle.

The officer drags the boy on the street like a sack of potatoes then drops him face first to the ground. During the brief 2014 incident, the boy, who was going to play Xbox with a friend, went into cardiac arrest and now suffers from brain damage. The traffic stop was based on a warrant from Kansas City, which turned out to be a mistake connected to the license plate on the vehicle the boy was driving. The officer claimed he also smelled marijuana and that the teen was being uncooperative.