The game is viewed from a first-person perspective. Initially armed with a standard-issue .38 service revolver, the player can acquire upgraded weapons during the course of play: a .357 Magnum, a semi-automatic pistol, a combat shotgun, an assault rifle, a submachine gun, or a grenade launcher. The submachine gun and grenade launcher can only be used once while other weapons can be reloaded like the service revolver. Losing a life reverts the player's weapon to the revolver. The game ends when all lives are lost, unless the player chooses to continue. Along the way, extra lives can be earned per 2,000 points scored. There are bonus points (10 each) for destroying certain targets. 8 points per enemy shot.
Lethal Enforcers has six stages (including the Training Stage): "The Bank Robbery", "Chinatown (on SNES, Downtown) Assault", "The Hijacking", "The Drug Dealers (on SNES, Gunrunners)", and "Chemical Plant Sabotage". During each stage, the player must shoot the armed robbers without harming any civilians or fellow policemen. One shot is enough to kill most enemies. At the end of each stage, a boss must be killed in order to complete the stage. A dip switch setting in the arcade version allows operators to let players progress through the stages in a linear fashion ("arcade mode") or select individual stages ("street mode").
Enemies always wear sunglasses, ski masks or gas masks, while fellow police officers and civilians are always barefaced. The boss character sometimes will have his face exposed; however, this battle is fought where there are no civilians present.
There are different ranks that the player can attain based on performance. The ranks are Patrolman, Detective, Sergeant, Lieutenant, Captain, and Commander. When the game begins, the player's rank is Patrolman, and after each stage the player is promoted, provided they have not killed any civilians. Killing civilians will cause the player to either be demoted or stay the same rank, although the ranks do not go below Patrolman.