Finally, after like 8 tries, I beat the goddamn level, covered in wounds everywhere except my head, barely crawling around the joint in pain.
I breezed through the next one in one try, without taking damage, or having to kill anybody, and got a perfect 100 score.
And then the next level after that I get killed by a robber before I can take down a single suspect.

If someone with a machinegun, body armor, and gas mask instead of fighting you flees so he can hide around a doorway or behind cover and shoot from you there, and you know that's what he's going to do, all his friends have done it, he did it last time you played before you were slaughtered like the ridiculous moral-bound fool you are, but if you shoot him preemptively before giving him a chance to lose you or riddle you full of bullets first, you get a "Unauthorized use of deadly force" penalty. :sad: Being a cop is hard.
I still don't get why I have to handcuff all the hostages and unarmed civilians in the area as well before the mission can be ended, either...