Abstract: A safety system for disabling a firearm and for maintaining the firearm in the disabled condition. The system is made up of a safety mechanism and personalized code key, which can be conveniently carried by the authorized operator, and which can be inserted into the handle of the weapon to be fired. The safety mechanism includes a specially designed safety lever which is maintained in a disabled, or safe condition, by a uniquely designed pawl element which positively prevents movement of the safety lever into a weapon-firing position until the pawl element is moved relative to the lever by a actuator mechanism of simple design which uniquely comprises a length of electricially conductive wire which shrinks when heated by an electrical current. With this construction, as the actuator wire shrinks, substantial forces are exerted on the pawl element of the system to move it out of the safe or gun-disabling position.