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Reducing gun violence in America.

The rate of gun violence in the United States substantially exceeds that of most other developed nations (1). Within the United States, gun deaths—particularly homicides—contribute to disparities in life expectancy between whites and minority groups, particularly African-Americans (2). Scientific progress in understanding how to address this problem has been limited in part because of limited research funding, which itself is largely due to the politics around guns in America (3). Therefore, the new article in PNAS by Luca et al. (4) addresses a critical topic.

In their new paper, Luca et al. argue that the adoption of mandatory waiting periods for handgun purchases reduces gun homicides by about 17%. These estimated effects are enormous. Most remarkable of all is that the policy intervention that leads to these reductions in gun violence would seem to impose so few costs on society. In what follows, I first try to put the magnitude of Luca et al.’s estimates into context to help readers appreciate how large they actually are. Moreover, if the results are correct, they would imply that that almost all gun violence in America is committed by people with only transitory motivation. However, it is also possible that their estimates overstate somewhat the effects of waiting periods on gun violence. This is not intended as a criticism; the question they address is intrinsically difficult. Refining our understanding of this question is likely to require better data systems in the future.

Their analysis also raises a natural follow-up question: If these laws are so helpful, why do only 16 states have such policies currently in place? The answer seems due in part to what has been called the “collective action problem” (5) that leads a small but highly motivated minority of the population to dominate the legislative process. This theory predicts that … 

[↵][1]1Email: jludwig{at}uchicago.edu.

 [1]: #xref-corresp-1-1