I find it interesting that Justice Roberts is so hot to enforce separation of powers, but not when it is the Judicial Branch that is involved. The doctrine of separation of powers, as promulgated by the Supreme Court, basically says that each branch of government is forbidden to encroach on the others. The powers of the legislative branch are very clearly laid out in the very first section of the Constitution. "ALL legislative powers granted are vested in a Congress". Legislative powers are what sets out our rights and responsibilities. Legislative powers define what is or is not a law, and what the penalties shall be for a violation. The granting of immunity is a legislative act. Hence it can ONLY be taken by Congress. Not the courts. Not even the SUPREME Court. The powers given to the courts are to enforce the law, not make it. Except apparently when John Roberts decides otherwise. His decision is unconstitutional not only because it purports to override the actual words of the Constitution, but in addition because he proposes to have the courts intrude on the powers given exclusively to Congress.
John Roberts and his henchmen are a threat to our Constitution, and hence to our democracy.