Barack Obama will leave office with one of the highest approval ratings for an outgoing president in U.S. history. Many respected and admirable people revere Obama. Family members, friends, journalists, and academics will appeal to your decent sensibilities, too. “Barack Obama was a great president,” they will say. And later: “We didn’t appreciate what we had until he was gone.” The tributes have already begun. Those sympathetic to such praise must reexamine Barack Obama’s presidency. Without an honest evaluation of Obama, the future abuses of Donald Trump cannot be credibly opposed. For the...