Vikram David Amar is the dean and the Iwan Foundation Professor of Law at the University of Illinois College of Law in Urbana-Champaign, and Akhil Reed Amar is Sterling Professor of Law at the Yale Law School. The opinions expressed in this commentary are solely those of the authors.

(CNN) In one of this year's most-watched cases, Trump v. Hawaii, Chief Justice John Roberts on Tuesday authored a five-justice opinion upholding the latest version of the Trump administration's so-called travel ban. While Roberts is the court's formal leader, Associate Justice Anthony Kennedy is often its fulcrum -- the proverbial swing justice -- and its conscience.

In the Hawaii case, Kennedy penned a brief and high-minded concurrence, epitomizing his approach to being a good judge and a good leader.

By joining Roberts' opinion, Kennedy kept his eye on the ball: the executive order itself, which regulates entry into the United States by nationals of several Middle Eastern and African countries, rather than the President's various inflammatory tweets about Muslims. (More on that later.)

As important as his swing vote was, Kennedy's words in concurrence are also noteworthy. In classic Kennedy fashion, he called for civility and mutual respect in an increasingly polarized country and world.

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Kennedy begins his concurrence by trying to identify "common ground" between all the justices in this case: everyone on the court abhors religious and other invidious discrimination. Finding common ground in contentious cases is what Kennedy has tried to do for decades. Sometimes, he votes with the liberals, other times the conservatives.

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