The Bartley-Fox Gun Law's Short-Term Impact on Crime in Boston

By making the illicit carrying of a firearm punishable with a one-year "mandatory" prison term, the Massachusetts (Bartley-Fox) gun law intervenes at what ap pears to be a critical juncture—from the standpoint of deterrent effectiveness and political feasibility—in the chain of decision that leads from the acquisition of a gun to its use in a crime. Drawing on FBI crime data, we employed interrupted time series techniques and multiple control group comparisons to examine the impact of the law on gun and nongun assault, robbery, and homicide. First, the law substantially reduced the incidence of gun assaults, but pro duced a more than offsetting increase in nongun armed assaults. Evidently, the law prevented some individuals from carrying and using their firearm, but it did not prevent them from becoming involved in assaultive situations and resorting to other weapons. Second, the law resulted in a reduction in gun robberies, accompanied by a less than cor responding increase in nongun armed robberies. In effect, weapons substitution effect for armed robbery was relatively less than for armed assault. Third, the law reduced gun homicides with no increase in nongun homicides. Thus the gun law produced a net decline in the incidence of criminal homicide. Finally, the timing of the law's impact suggests that it was the publicity about the law's intent rather than the severity or certainty of the punishments actually imposed under the law that was responsible for the observed reduc tions in gun-related crimes.