If justification requirements are presemt (Intent, Weapon, Delivery System) then you must achieve three "target requirements" before discharging your firearm. The first is "target identification".
This means that you positively identified the target/threat. An example is that you heard a gun shot and see a muzzle flash in the darkness. Before you blindly return fire you must positively identify the threat before you return fire where that muzzle flash and gun fire originated from. What if that shooter was behind in innocent victim such as a hostage that he was using as a "body shield". Simply returning a shot in that direction without illuminating or confirming what your target is could result in a very horrific outcome. A car speeds by and commits a drive-by shooting, you would not want to fire a wild shot in to the car that is speeding by without having a specific target. Always be sure of your target and what's beyond as they say in safety class.
See you tomorrow when I will explain the 2nd target requirement, "target isolation".