Steve Verdon comments on the Ayres and Donahue study I cited yesterday. Unfortunately he doesn't seem to have understood what their conclusions were. Try reading the abstract, Steve:
"Estimating more statistically preferred disaggregated models on more complete county data, we show that in most states shall issue laws have been associated with more crime and that the apparent stimulus to crime tends to be especially strong for those states that adopted in the last decade."
Now this study is correlational, so it certainly doesn't prove that carry laws cause more crime, but if you believed that Lott's correlational study proved that more guns caused less crime you should also believe that Ayres and Donahue have now proved that more guns caused more crime.