University of California - Irvine law school Professor Rick Hasen (author of the book The Supreme Court and Election Law) has an interesting blog about election law at this easy-to-remember address:
Among other things, Hasen points out that there have in recent decades been a handful of cases in which elections were in all likelihood stolen by fraudulent absentee ballots, but none at all involving in-person voter impersonation, the type of supposed election tampering addressed by voter-ID laws.
Incidentally, before 2006, not one U.S. state required people to show an ID before voting. Now 30 do.
These laws no doubt prevent some in-person voter fraud, but that problem scarcely exists. At the same time the laws also unquestionably keep many American citizens, especially the poor and elderly, from voting. They distort elections vastly more than the supposed problem they're meant to address.
Incidentally, Jonathan Bernstein has a good response in Greg Sargent's Plum Line blog to a recently resurrected bogus claim of voter fraud in Wisconsin that (as he points out) voter ID laws would not have prevented even if the claims were correct.