Is intelligence associated with mortality from lethal force by law enforcement?

Intelligence (IQ) has emerged as an important determinant of many social and health outcomes, and is associated with criminal behavior. This ecological study tested whether IQ was associated with the use of lethal force by law enforcement by examining estimates of state IQ and mortality from lethal force in 50 U.S. states. These data were obtained from a variety of sources freely available on the Internet, including information about mortality from lethal force from a database compiled by a news website, The Guardian. State IQ was negatively correlated with the rate of people killed by law enforcement (r = −0.50, p < .01). This association persisted even after adjusting for numerous demographic and social characteristics; each point increase in state IQ was associated with a 6% reduction in the rate ratio of deaths from lethal force (IRR = 0.94 [95% CI = 0.90, 0.98]). States with higher IQs may have safer communities, and law enforcement officers may act less confrontationally or hostilely during police-suspect encounters in these areas. However, this hypothesis needs to be investigated in future studies using smaller aggregate units for IQ and include more information about neighborhood, law enforcement, and suspect characteristics.