A study sought to evaluate whether more firearms cause more or less crime. Through the evaluation of the Statute of Disarmament, the authors concluded that the policy applied in the state of São Paulo between 2001 and 2007 was one of the factors that led to the reduction of homicides in that state [1].
A second study evaluated the application of the Statute of Disarmament in the state of São Paulo. The authors used the level of gun suicides as a proxy for the number of guns available in the city at baseline. They estimated considerable reductions in homicides (at least 12.6%, which would represent 2,000 lives between 2004 and 2007, a figure that could reach 2,750 lives). However, the study found no impact on the rate of property crime (or auto theft, specifically) [2].
Finally, a third study sought to understand the relationship between the volume of firearms and the homicide rate. Using the context of increased repression against illegal gun carrying and the creation of the Disarmament Statute between 1997 and 2007, the authors studied this relationship for the state of São Paulo. The results suggest that a 1% reduction in the stock of firearms reduces, on average, the homicide rate per 100,000 inhabitants by 0.15% – 0.20% [3].