Abstract: An authorization system for a firearm includes a personal device worn by the authorized user, modifications to the firearm's fire control system, and an authorization control circuit carried in the backstrap of the firearm handle. The authorization control circuit controls the fire control system and communicates with the personal device. In particular, the authorization control circuit will send a first coded signal to the personal device via an ultrasonic transponder and wait for a coded response. If the personal device is worn by a user and is within range, properly oriented and has received a correct code, it will respond to the signal by sending a coded response. If the correct coded response is not received, the authorization control circuit signals a brake solenoid located near the trigger bar to move to a locked position where it will cam the trigger bar out of engagement with the sear as the trigger is pulled. Consequently, the trigger bar will not move the sear and the firearm will not fire.