Secondary to the primary horror of Trump's current attempts to apply this to citizens: It is also a direct attack on one of the other key points of societal failure, which is trust in police. Yes, yes, we were already way below where we need to be, but it was still the case that when an innocent non-black person encountered police, the majority of the time the feelings they might have ranged from trust to simple nervousness. An enormous caveat to law enforcement is that we trust officers with the power to order people to do things. If a cop orders me to come with them without a great explanation, I'm going to verbally protest, ask to see their badge, whatever - but I'm going to physically comply, because we agree to give cops this power, and, crucially, because there could be a legitimate reason, or an innocent mistake, and even absent that, I have a general feeling about the ceiling on the worst things that could realistically happen to me (since I'm a citizen, white, etc).

But now, a bright line has been crossed. Anybody in a group that Trump supporters hate has to consider that there is a non-zero chance an encounter with the wrong type of law enforcement could end with being tortured in a foreign prison. In a nation governed by fear, my mind is not nearly as clear on priorities and risk assessment when the cop asks me to come with him without a rock solid explanation. That's dangerous, for everybody, including the police.