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Abstract
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BACKGROUND: In November 1986, a Detroit, Michigan city ordinance requiring mandatory jail sentences for illegally carrying a firearm in public was passed to preserve "the public peace, health, safety, and welfare of the people." METHODS: We conducted a set of interrupted time-series analyses to evaluate the impact of the law on the incidence of homicides, hypothesizing that the ordinance, by its nature, would affect only firearm homicides and homicides committed outside (e.g., on the street). RESULTS: The incidence of homicide in general increased after the law was passed, but the increases in non-firearm homicides and homicides committed inside (e.g., in a home) were either statistically significant or approached statistical significance (p = .006 and p = .070, respectively), whereas changes in the incidence of firearm homicides and homicides committed outside were not statistically significant (p = .238 and p = .418, respectively). We also determined that the ordinance was essentially unenforced, apparently because of a critical shortage of jail space. CONCLUSIONS: Our findings are consistent with a model in which the ordinance had a dampening effect on firearm homicides occurring in public in Detroit. The apparent preventive effect evident in the time series analyses may have been due to publicity about the ordinance, whereas the small nature of the effect may have been due to the lack of enforcement.
VioLit summary:
OBJECTIVE:
The purpose of this study by O'Carroll et al. was to assess the effect of a Detroit, Michigan city ordinance requiring mandatory jail sentences for illegally carrying a firearm in public.
METHODOLOGY:
The ordinance was passed in November, 1986, and became effective on January 10, 1987. With a quasi-experimental design the authors conducted a set of interrupted time-series analyses to evaluate the effects of the law by contrasting the monthly incidents of homicides before and after the ordinance wa implemented. The intervention analysis developed by Box and Tiao was used, based on the Box and Jenkins autoregressive, integrated, moving average (ARIMA) modeling of time series. This analysis controls for variables which influence th homicide rates consistently over time, allowing for an appropriate estimate of the effects of the law. Two separate monthly analyses were conducted, one for firearm versus nonfirearm homicides, and one for public versus nonpublic homicides (all estimates were computed using the backforecasing algorithm implemented in BMDP2T software). Data were analyzed from 1980 through 1987 from the Official Complaint Report records of the Detroit City Police Department. All homicides were included in the data, including murder, murder 1st degree, murder 2nd degree, and manslaughter. The homicides were then divided by 1) firearm or some other means and 2) inside a building or outside. Four cases in which the homicide method code was missing and 73 cases coded as unknown were assigned to the nonfirearm series under the rationale that firearm homicides are easily recognized. In addition to this statistical analysis, interviews were conducted with individuals whose jobs involved implementing the ordinance or processing th defendants, in order to supplement the data with perceptions regarding the enforcement of the ordinance.
FINDINGS/DISCUSSION:
Although the ordinance did not stop the surge of violence, it may have had a dampening effect as the homicides committed outside increased by 10 percent, while those committed inside increased by 22 percent. The increase in inside homicides was large relative to its standard error and therefore unlikely to be due to chance (p=.006); however, the increase in outside homicides was small (p=.418). The incidence of nonfirearm homicides increased 16 percent after the ordinance (p=.07). Although the incidence of firearm homicides increased almost as much, the change was not statistically significant by conventional standards (p=.24). In sum, the increases in the two types of homicide that were targeted by the ordinance did not emerge as statistically significant, which is what woul be expected if the ordinance had a dampening effect on firearm homicides and outside homicides. The design of the research, however, assumed that the law would change the number of mandated jail sentences as a consequence of illegally carrying a firearm, and the records do not suggest an increase in sentencing; of the 1,020 persons charged as of early 1989, only 22 were sentenced to jail. In corroborating these figures, the criminal justice personnel who were interviewed noted that very few of the arrests ultimately led to the mandatory sentencing; the ordinance was almost completely unenforced. Because of the lack of enforcement, the findings of this research cannot be considered definitive.
AUTHORS' RECOMMENDATIONS:
Despite the appeal of gun ordinances, which regulate who can legally carry loaded firearms (and are therefore less subject to the controversy surrounding more aggressive gun control efforts), the costs of arrest, adjudication and mandatory incarceration are significant. Without consistent enforcement of such measures, their effect and their cost cannot be appropriately assessed. When suc laws are passed and enforced, rates of injury and death from public firearm violence should be thoroughly researched, as should the cost of implementing these measures.
(CSPV Abstract - Copyright © 1992-2007 by the Center for the Study and Prevention of Violence, Institute of Behavioral Science, Regents of the University of Colorado)
N1 - Call Number: F-545, AB-545
KW - 1980s
KW - Michigan
KW - Firearms Control
KW - Firearms Homicide
KW - Firearms Violence
KW - Legislation
KW - Program Effectiveness
KW - Program Evaluation
KW - Mandatory Sentencing
KW - Offender Sentencing
KW - Correctional Decision Making
KW - Criminal Justice System
KW - Adult Firearms Carrying
KW - Adult Offender
KW - Adult Violence
KW - Juvenile Firearms Carrying
KW - Juvenile Offender
KW - Juvenile Violence
KW - Firearms Carrying Effects
KW - Homicide Prevention
KW - Violence Prevention
KW - Prevention Program
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