The Impact of Right-to-Carry Laws and the NRC Report: Lessons for the Empirical Evaluation of Law and Policy

Abstract

For over a decade, there has been a spirited academic debate over the impact on crime of laws that grant citizens the presumptive right to carry concealed handguns in public— so-called right-to-carry (RTC) laws. In 2005, the National Research Council (NRC) offered a critical evaluation of the ‘‘more guns, less crime’’ hypothesis using county-level crime data for the period 1977–2000. Seventeen of the eighteen NRC panel members essentially concluded that the existing research was inadequate to conclude that RTC laws increased or decreased crime. The final member of the panel, though, concluded that the NRCs panel data regressions supported the conclusion that RTC laws decreased murder. We evaluate the NRC evidence and show that, unfortunately, the regression estimates presented in the report appear to be incorrect. We improve and expand on the reports county data analysis by analyzing an additional six years of county data as well as state panel data for the period 1977–2006. While we have considerable sympathy with the NRCs majority view about the difficulty of drawing conclusions from simple panel data models, we disagree with the NRC reports judgment that cluster adjustments to correct for serial correlation are not needed. Our randomization tests show that without such adjustments, the Type 1 error soars to 40–70%. In addition, the conclusion of the dissenting panel member that RTC laws reduce murder has no statistical support. Finally, our article highlights some important questions to