It seems, lately, that there is a clearer-than-ever delineation between legality and enforceability. If our government commits an illegal act, who is able to enforce it? Who's able to hold them accountable? I wish I could say I had a good answer to that question.
The answer to your question is the same answer that's included in the Constitution, the same answer that's always been the ultimate answer to all out-of-control governments.
You. The citizens.
You and others that would be willing to put your lives on the line when all other options have been shown to be worthless/ineffective, to pick up a sniper rifle, build an IED, make Molotov cocktails, organize and plan, and target the criminal leaders and take them out..
There are still a few peaceful options left to try yet, like the recent push for a convention of States to amend the Constitution to rein in the Federal government.
However, if the government steps in to stop such reforms, there will be no alternatives left.