On April 11, Roy Cooper, the North Carolina Attorney General, announced that he was dropping all charges against the three Duke lacrosse players who had been indicted for kidnapping and raping a black stripper in March 2006. As Mr. Cooper stressed, he was dropping the case not because there was insufficient evidence—often a euphemism for “probably guilty, but we can’t prove it”—but because the three players were innocent of the charges that had recklessly been brought against them. Mr. Cooper went further: not only had there been “a tragic rush to accuse and a failure to verify serious allegations,” but the case also showed “the enormous consequences of overreaching by a prosecutor.”

In fact, the Duke lacrosse case showed a number of things. Yes, there was the issue of the disgraced District Attorney Michael Nifong running amok, suppressing evidence and cynically bartering the ...