When district and appeals courts do what they like, the SCOTUS can reverse every one of their decisions. The inferior courts can then go on a spree of incorrectly deciding every relevant case and delay the final judgement by years, but then the SCOTUS could just speed up its process of reversing every such decision by the inferior courts. The SCOTUS also has options for removing judges from certain types of cases, IIRC. It's a game that the SCOTUS invariably wins in the end -- unless it gets packed.
There has been times in the past where the other branches ignored the Supreme Courts rulings. They cannot call out troops. The only people that give them power are the other branches that enforce those rulings, but they could decide not to.
I think if we got to the point that we could not rely on Supreme Court rulings being upheld without the mobilization of troops, we will already be in a situation of fundamental institutional collapse anyway, and questions of constitutionality and legality of anything will become moot as we descend into a raw state of nature.
