The question of whether armed citizens deter violent crime or exacerbate it has been controversial in academia since at least the mid-1990s—not to mention the debate it continues to fuel in American politics. Conflicting studies have informed polarized lawmakers in the parallel battles over gun regulation.
The case for less restrictive gun laws generally boils down to this: Law-abiding citizens have a right to protect themselves and their communities, full stop. The academic backing for this argument can be traced to a 1997 study by University of Chicago economists John Lott and David Mustard. After analyzing the impact of “right-to-carry” laws, the umbrella term for various legislation that allows citizens to acquire a concealed-carry gun permit, the authors concluded that these regulations were “the most cost-effective method of reducing crime thus far.”
The researchers built fictional, or “synthetic,” states as near-identical counterparts to the 33 that passed right-to-carry laws between 1981 and 2014. Using the states’ crime rates prior to the laws’ adoption, as well as national crime data from before and after, they created an algorithm to estimate what trends would have been prevalent had these areas never passed right-to-carry. The researchers then compared crime in the real states with findings from their synthetic versions.