Abstract: A system for locking a firing mechanism of a firearm in response to blood-alcohol content can include a breathalyzer system and a lock system. The breathalyzer system can be configured to connect to a firearm and include an input port for receiving fluid and a processing module for analyzing blood-alcohol content of the fluid. The lock system can be configured to connect to the firearm and be operably connected to the breathalyzer system for receiving a signal from the breathalyzer system so as to disable a firing mechanism of the firearm in response to the blood-alcohol content of the fluid being sensed to be above a threshold.