It's the Constitution. Presidents can fire any subordinate they wish to for any reason and at any time. Any law that Congreff would pass protecting Mueller would be struck down immediately by SCOTUS. --at least for now while the court still has Constitutionals on it. I imagine this one would be even go 9-0 even with the 4 progressives on the court as it's cut and dried. --Make no mistake---Mueller should be fired, but it isn't politically the right thing to do. Although, that may be changing.--Izzy