i've always heard it characterized as they must "control the scene", and to achieve that control anything is permissible, especially swift overwhelming action to preempt a potential, predicted loss of control and since swift action is the tactical play, it's just fine to take action before understanding the situation. unknown = possible threat = actionable threat = target.

what kinda blows my mind is how the mouthpieces openly state and justify the instances where disproportionate violence has been recognized in a specific case by saying, "well, police want to go home safe at the end of the day like everybody else." if you want to be safe at work, don't sign up to be a cop and stop pretending to be a hero. you don't see people afraid of fire signing up to be fire fighters. i mean, cop is not even in the top 10 of dangerous jobs in the US, where supposedly [but not really] everyone is armed, but they sure as hell love to be exalted as selfless heroes of the community.

they claim to be the defenders of a community and claim the self-sacrificing honor of putting themselves in harm's way but never miss an opportunity to deploy all the weapons and gear provided to take the easiest, self-preserving route every time to obliterate an unknown person or bystander's entire life if means avoiding a scratch on their shooting glasses.

hell, half the time the cop's justification for blowing someone away is that the cop's gun was the threat and they accuse the dead person of thinking about grabbing their gun. wrap your mind around that one: the cop is the only one armed in a room and the existence of the cop's gun is what justifies the shooting of unarmed people by the cop. it's even used as a threat by cops "i can tell them later you reached for my gun." cops in the US should not be allowed to carry guns. easiest step #1 in getting a lot of the trash to take itself out.