Washington (CNN) President Donald Trump's persistent and unprecedented criticisms of judges and the judiciary at large have incited outrage on both sides of the legal community and prompted some to wonder if Chief Justice John Roberts should publicly come to the defense of his robed colleagues.

The chief justice also heads the Judicial Conference of the US -- the policy making body for the federal courts — and has defended his fellow jurists before. But Roberts has remained silent.

Some have called for Roberts to issue a statement. Richard L. Hasen of the University of California Irvine wrote recently, "There is someone else who should speak up for an independent judiciary, and that's the Chief Justice."

But that is not likely to happen. Roberts walks a careful line supporting the judiciary but keeping it far from the political dysfunction that has consumed the other two branches. When a political storm erupts, he strategically decides when to insert himself.

Like most judges, Roberts treasures the idea of impartiality, and he also cares more than most about the legitimacy of the courts. As such, often his rule is to refrain from entering the immediate fray, but to circle back when the winds have died down.

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