“It is emphatically the province and duty of the Judicial Department to say what the law is,” United States Chief Justice John Marshall declared more than 220 years ago. Indeed, judicial independence with the power of judicial review is the crown jewel of the Constitution. It is the thin line between order and chaos.

We live in raucous political times. That’s a given. We need an adult in the room. That’s why Chief Justice John Roberts deserves a shoutout this week for standing up to bullying coming out of the Republican Party with calls for the impeachment of judges who rule against President Donald Trump in discharging their duty to say what the law is. We can’t have the executive branch be a judge in its own cases contrary to centuries of Anglo-American jurisprudence. To be sure, judges are not infallible. But they operate with procedural safeguards against error absent in the White House or Congress.

Roberts’ statement issued on Tuesday rightfully points out that the judicial branch is constitutionally entrusted with reviewing the legality of executive actions whether pioneering or otherwise. U.S. District Judge James Boasberg interpreted the Alien Enemies Act of 1798 according to its text, i.e., that it applies during declared wars or when a foreign government or nation has invaded the United States. The district judge rejected the argument that an alleged Venezuelan gang was engaged in guerilla warfare against the United States in cahoots with the Venezuelan government based on a naked assertion of Trump. But the judicial process does not stop with Judge Boasberg. Trump can take his case to the U.S. Court of Appeals and ultimately to the United States Supreme Court. That’s how the rule of law works.

Trump’s posting statements denigrating Boasberg as a “Radical Left Lunatic of a Judge” who should be “IMPEACHED!!!” were wildly misplaced. The U.S. chief justice’s response was a model of moderation: “For more than two centuries, it has been established that impeachment is not an appropriate response to disagreement concerning a judicial review.”

Federal judges are appointed as guardrails against the political branches. They interpret the law without fear or favor according to time-honored canons of construction that constrain judicial whimsy. They need protection from political bullying or threats that have climbed to alarming levels. They should not need Secret Service protection.

Chief Justice Roberts should be encouraged to speak out again if the time arises as the Trump administration launches trial balloons about disobeying court orders. The chief justice has shown he is committed to defending the crown jewel of the Constitution. We should all be thankful.