Graph on correlation between "shall issue" and homicide rates
Over at No Lawyers, Only Guns and Money. Essentially, as "shall issue" rapidly spread, homicide rates rapidly fell. They draw, I think, the sound conclusion that "Violent crime is a complex issue, but national data is clear that there is no positive correlation between liberalized concealed carry laws and increased violent crime." Coincidence doesn't prove causation, but lack of coincidence certainly raises serious questions about lack of causation.