By the authority of the violence at its command and the absolute refusal of the other branches of government to exercise the checks and balances against it, and the repeated certification of this behavior by voters who vote the same idiots into Congress every single election cycle at a rate of 95% or more.
This country chucked “Rule of Law” in the garbage long ago, so now we have the rule of violence.
Having spent decades trying to get people to recognize the importance of the rule of law and failing against every tide of mob passion that has washed over the country since, all I can do at this situation is shake my head at the insanity demonstrated by everyone involved. People often assume that in a conflict one party is right and the other is wrong, and never consider that both parties are wrong.
> By the authority of the violence at its command
In other words, no authority at all.