I would say Trump lost his mind, but not sure whether he ever had a sane mind.
Without having read the entire discussion, but as far as I remember this (martial law) can only happen with congressional approval. No way this gets through.
Of course not; it violates Posse commitatus. But since when has that stopped the chicken little critics. It must be exhausting switching between "OMG Trump said this thing and if you construe it hyper literally it sounds bad. We should trust him to do this bad thing." And "OMG it doesn't matter what Trump says. We can't trust him when he says he wont do the bad thing." I mean Obama "sent feds" to investigate a parade float in Nebraska. "Sending feds" does not have to mean the absolute worse interpretation possible. Doing what you fear is unconstitutional. It won't happen and no amount of Bill Maher level fear mongering about "muh Trump is uh Nazi Fascist and will genocide everyone" will change that.
