Responding to myself, but this is my fundamental issue with the Trump administration.
I fundamentally disagree with its platform but, living in a democracy, you have to accept that sometimes the government will be one with which you vehemently disagree on matters of policy.
It is also true that most governments will, at some point, carry out (or attempt to carry out) actions that are of dubious legality - if the judiciary determine illegality, a government that thinks it has a case may continue to fight it within the confines of the judicial system but, ultimately, they will accept the legitimacy of the courts. That's the Rule of Law, and its an essential feature of any true democracy.
It's not the policies, nor the rhetoric and lies, that make me think the Trump administration is the most uniquely dangerous administration the West has seen since WW2 - it is the utter contempt for the law (including the constitution).
Supporting the Trump administration - and supporting ICE - is supporting criminality and opposing basic, settled laws.
And yes, contempt for the Rule of Law is absolutely one of the key operating principles of facism, and is what is unfolding in the US right now.