Someone inspected Donohue and Levitt's code and found a bug that meant they hadn't controlled for what they claimed they had. "Fixing that error reduces the effect of abortion on arrests by about half, using the original data, and two-thirds using updated numbers."
Via http://election.princeton.edu/2012/12/22/scientific-american, which cited Reyes' work on the lead theory, here's a link to a striking critique of the abortion theory:
http://www.economist.com/node/5246700?story_id=5246700
Someone inspected Donohue and Levitt's code and found a bug that meant they hadn't controlled for what they claimed they had. "Fixing that error reduces the effect of abortion on arrests by about half, using the original data, and two-thirds using updated numbers."