It's quite simple & logical, really. Responding officers are esentailly assigned a job to do at the call. One officer is the contact officer--the person who'll actually talk to the subject. Depending on the nature of the call & its locale another may be assigned a less-lethal force (stun-bag, taser, etc.) and one, perhaps two will be assigned as a shooter. It's the shooters responsibility to decide when to shoot. He is the sole person(s) whose job it is to neutralize the threat with lethal force at his discretion within Dept. policy. This avoids the risk of cross-fire, sympathetic respones from other officers & allows the responding officers to use less-lethal force if practical.
