We’re on unfamiliar ground now. No president before has sought to punish his predecessor for policy decisions, no matter how wrong or wrong-headed. Lyndon B. Johnson’s management of the Vietnam War was often ham-handed, as anyone who was there could tell you, and his policy makers sometimes verged on criminal incompetence. But Richard Nixon was never tempted to send LBJ or any of those presidential acolytes to prison. Abraham Lincoln, by his lights, would have had ample opportunity to hang Jefferson Davis and Robert E. Lee, but even the rabid Republicans who survived the assassination stopped short of putting Davis in the dock, finally releasing him from imprisonment at Fort Monroe when judgment overcame lust for revenge. Lee was never touched.

Exacting revenge for unpopular policies is the norm in the third world, heretofore more likely in Barack Obama’s ancestral Kenya than in America, more in the tradition of gangland Chicago than in Washington, where we count on cooler heads to prevail when raw emotion threatens to overwhelm sobriety and the undisciplined senses. We recall perceived national mistakes with the sadness of regret and even gratitude for lessons learned, not the frenzied catharsis of a St. Valentine’s Day Massacre. Mr. Obama, having won the White House fair and square, is entitled to change any presidential policy he chooses, but the vindication of a national election does not entitle any president to exact mindless revenge.