That would be fine if it stayed that way – but the Leftist-Marxists are all about Incrementalism.
They will start from there and with each crisis ratchet the screws a little tighter.
That is what happened to the Constitution. It was ours to keep. Hence, this is not so much about the structure of how such decisions are made but about the mindset of the people. No matter what, no one can devise a system that can preclude the consequences of depravity in the general population. Hence, your concern is misplaced.
BTW, having just finished Balko's book on the topic, I'm well apprised of the concerns you related about militarization of the police.