Paul Heroux has this as part of his post up at the Huffington Post:
Economist John Lott likes to point out that wherever there has been a gun ban we have seen crime increase. Lott has specifically made the point concerning England's 1997 gun moratorium. Unfortunately, this example is a little loose with the statistics. In some countries where an increase in gun homicides followed a gun ban, it was part of an already rising trend, as it was in England. In other cases it followed the ban. In short, there is no causal relationship; the relationship is spurious. Additionally, Lott also said that he did not accept that the US is the leader in gun homicides in the developed world. This flies in the face of the facts.
If you want to see how wrong Mr. Heroux is about this claim on how murder rates changed after the UK handgun ban see the figures available here
Lott has also noted that the common denominator of the recent mass shootings is that they all occurred in a gun free zone. This implication is that the shooters targeted the zones because they were gun free. This can't and won't be proven, and it is unlikely anyway. First, we know that students all over America carry guns to schools every day, so schools are not really gun free. Second, Fort Hood is a military base with lots of guns, and Virginia Tech is a university with its own police force. Third, there is more reason to believe that the recent mass shootings targeted the people at the locations because of who they were, not because of where they were. The presence or absence of a gun ban is spurious. . . .
There are 41 right-to-carry states. What gun-free zones mean places where law-abiding citizens are not allowed to carry concealed handguns. The ban is with respect to law-abiding citizens, not police. Yet, with Fort Hood, soldiers are actually forbidden from carrying around guns on army bases (see here
for a discussion). As to the claim that "the recent mass shootings targeted the people at the locations because of who they were, not because of where they were" please see this article.