Five Justices defend the Constitution against anti-Trump passions.

Donald Trump is so polarizing that a test of his Presidency is whether American institutions can keep their bearings and hold to principle despite the passions of the moment. Five Supreme Court Justices did the country a service on Tuesday by sticking to the Constitution and rule of law on executive power rather than succumb to the temptation to rebuke an unpopular President’s dubious policy. A 5-4 majority upheld Mr. Trump’s third “travel ban” from 2017 that restricted entry to America from eight countries. The ban in our view isn’t necessary, and the Court made no judgment on the policy merits. But Chief Justice John Roberts and four conservative Justices found that the ban falls well within the President’s core national-security powers. This is less a victory for Mr. Trump than for the ability of future Presidents to defend the country.

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