VIII. Deterrent Effects of Gun Ownership Among Potential Victims
Evidence also indicates that some criminals may be deterred from making criminal attempts in the first place by the possibility of victims using guns against them. Criminals interviewed in prison indicate that they have refrained from committing crimes because they believed a potential victim might have a gun (Kleck, 1997). Likewise, anecdotal evidence indicates that crime rates have dropped substantially after highly publicized instances of prospective victims arming themselves or being trained in gun use, or victims using guns against criminals. Evidence also supports the hypothesis that U.S. burglars are careful to avoid residences where the victims are home because they fear being shot. Whereas 43% of British residential burglaries are committed while victims are home, only 9% of residential burglaries in the United States are committed under such circumstances (research summarized in Kleck, 1997). None of this evidence is strong or decisive; instead, one can say only that it is consistent with the hypothesis that criminals are deterred from attempting some crimes by the possibility of confronting a victim with a gun.
IX. The Net Effect of Gun Ownership Levels on Crime Rates
The research on gun use by victims has yielded very consistent results: It reduces the likelihood of injury or property loss. Thus, gun possession among largely noncriminal prospective victims has beneficial effects. On the other hand, gun possession among criminals has a mixture of both harmful and inadvertently beneficial effects. Consequently, the net effect of overall gun ownership levels on violence rates is not self-evident on the basis of the research discussed earlier.
Dozens of studies of the effect of gun ownership levels on crime rates in macrolevel units such as cities and states have been conducted, but most of the research is seriously flawed. In particular, most studies have failed to properly model the possibility of a two-way relationship between violence rates and gun ownership rates, making it impossible to interpret the meaning of a positive association between the two (Kleck, 1997). Although more guns may lead to more crime, higher crime rates may motivate more people to acquire guns for self-protection. Likewise, most of these studies did not use measures of gun levels that are known to be valid—the researchers were actually measuring something other than gun ownership levels, making it impossible for them to assess the effect of gun levels.
Most of this research has found no effect of gun levels on rates of robbery or aggravated assault. The evidence on homicide rates, on the other hand, is much more mixed, although studies that have used validated measures of gun ownership and that addressed the possible two-way causal relationship mostly have found no net effect of gun levels on homicide rates (Kleck, 1997, Chap. 7). The most sophisticated recent research indicates that the net effect of overall gun ownership (both criminal and noncriminal gun ownership combined) on homicide is actually negative; that is, overall gun levels reduce the homicide rate, probably because the homicide-reducing effects of noncriminal gun ownership outweigh the homicide-increasing effects of criminal gun ownership (Kovandzic et al., 2005). Because this research relied on highly complex statistical procedures, however, one can be confident that these findings will be challenged.