Fascinating piece called Better Judgment:

Posner’s attention to consequences can lead him, like other empirically minded judges, to change his thinking. Eight years ago in Crawford v. Marion County Election Board, an early challenge to a state law requiring voters to show photo identification at the polls, Posner ruled in favor of Indiana’s voter-ID law, in part because none of the plaintiffs who challenged it said that the law would prevent them from voting. Dissenting from Posner’s ruling, one of his colleagues said that Indiana, too, lacked evidence of the existence of voter fraud, which the law was ostensibly intended to combat. It was clear enough, the colleague wrote, that thousands of poor and elderly voters would be disenfranchised.

Six years later, in “Reflections on Judging,” a recent book (he has written roughly 45), Posner criticized his original ruling. “I plead guilty to having written the majority opinion,” he wrote, upholding “a type of law now widely regarded as a means of voter suppression rather than of fraud prevention.”

Commentators pounced: A New York Times headline trumpeted “The Debate Over Judge Posner’s Unforced Error,” and The Washington Post ran a column titled, “Judge Posner’s Mea Culpa Was Better Left Unsaid.” The lesson was clear: It’s safer for judges not to admit misgivings.

But Posner said he had simply acknowledged that judges sometimes don’t understand a subject well enough to “gauge the consequences of their decisions.” With more evidence about the results of requiring voter ID, it made sense to him to shift his position. Last year, Posner’s court heard a challenge to another voter-ID law in Wisconsin. Researching online, Posner found charts showing that strict voter-ID requirements have been enacted only in states controlled by Republicans. After a panel of three judges on his court upheld Wisconsin’s law, Posner urged the court as a whole to rehear the case. This time he wrote that the “net effect of such requirements is to impede voting by people easily discouraged from voting, most of whom probably lean Democratic.” Posner lost the argument; the panel decision was upheld and Wisconsin’s law stood.

Even the architect of the Supreme Court’s voter-ID decision has had a change of heart. In 2008, Justice John Paul Stevens wrote the majority opinion affirming Posner’s Indiana ruling by a vote of 6 to 3. But he, too, has since decided that the dissenting judges got it right about the consequences of the decision. It’s “unfortunate,” Stevens told me by phone recently, that his opinion in Crawford has prompted other states to pass voter-ID requirements.