The motorist who accused OJ Simpson of road rage chased the former football star to scold him and provoke a confrontation, a court has heard.
Simpson is accused of reaching inside Jeffrey Pattinson's car, grabbing his glasses and scratching his face.
Simpson says the altercation has been blown out of proportion.
Defence attorney Yale Galanter told the court: "Pattinson became a vigilante. That's what he does. He doesn't seek out help. He wants to play cop instead of calling a cop."
Simpson faces up to 16 years in prison if convicted of auto burglary and battery in the dispute with Pattinson last year in Miami.
Prosecutors say Simpson, 54, drove through a stop sign, then stopped after Pattinson honked his horn and flashed his lights. Simpson said Pattinson was "sitting on his horn".
Simpson denies reaching into Pattinson's car and said the men confronted each other outside their sport utility vehicles.
He said Pattinson lied about staying in his car, which led prosecutor Abbe Rifkin to ask yesterday if Simpson would ever lie, "especially if your life depended on it".
Simpson responded: "I've never been put in that position to have to lie with my life on the line."
Pattinson had testified that he stayed in his vehicle, that Simpson stormed at him and that he asked Simpson if he was "a madman or something".