In response to a congressional mandate for an impact assessment of the Federal Violent Crime Control and Law Enforcement Act of 1994, which bans a group of military-style semiautomatic firearms (i.e., assault weapons) and ammunition magazines capable of holding more than 10 rounds, this study used national and local data sources and a variety of analytical techniques to examine the ban's short-term impact on gun violence.
The study also considered the issue of statistical power in legislative impact evaluation under two conditions that the legislative process may impose: short statutory mandated follow-up periods for evaluation and legislative compromises that result in modest policy changes that are likely to have limited impacts. Ban advocates argue that assault weapons are particularly dangerous because they facilitate the rapid firing of high numbers of shots. Although the banned guns and magazines were used in only a modest fraction of gun crimes before the law, it was hypothesized by supporters of the law that a decrease in their use might reduce gunshot victimization, particularly those that involve multiple wounds and/or victims. Findings show that the ban may have contributed to a reduction in gun homicides, but a statistical power analysis of the model used showed that any likely impact from the ban will be difficult to detect statistically for several more years. There was no evidence of reductions in multiple-victim gun homicides or multiple-gunshot wound victimizations. The findings should be viewed cautiously due to the methodological difficulties of making a short-term assessment of the ban and because the ban's long-term effects could differ from the short-term impacts revealed by this study. 7 tables, 2 figures, and 49 references