The people's hired guns? Experimentally testing the motivating force of a legal frame

Legal realists expect prosecutors to be selfish. If they get the defendant convicted, this helps them advance their careers. If the odds of winning on the main charge are low, prosecutors have a second option. They can exploit the ambiguity of legal doctrine and charge the defendant for vaguely defined crimes, like "conspiracy". We model the situation as a signaling game and test it experimentally. If we have participants play the naked game, at least a minority play the game theoretic equilibrium and use the broad rule if a signal indicates that the defendant is guilty. This becomes even slightly more frequent if a misbehaving defendant imposes harm on a third participant. By contrast if we frame the situation as a court case, almost all prosecutors take the signal at face value and knowingly run the risk of losing in court if the signal was false. Our experimental prosecutors behave like textbook legal idealists, and follow the urge of duty. The experiment demonstrates the strong behavioral force of a legal frame.