Firearm Injury Interventions

Mandatory Sentencing

Background

One legislative strategy to reduce injuries from guns is mandatory minimum or additional prison sentences for people convicted of specified crimes while in possession of a firearm. These laws are based in the hypothesis that, by decreasing the number of persons carrying firearms, the incidence of firearm violence will decrease. One would expect that the laws would have their greatest effects on shootings occurring in public places since these laws to not address the issues of keeping firearms at home.

Many jurisdictions have passed such legislation. Evaluations have appeared both in the criminology literature as well as in the public health literature. Here, we review 6 such studies.


Review of mandatory sentencing legislation studies:

Author

O’Carroll et al., 1991

Study design and target population

Time series analysis. Population: Detroit, MI 1980-87.

Intervention

1986 city wide ordinance in Detroit, MI. Mandatory jail sentence for concealing or carrying firearms.

Outcomes

Incidence of firearm homicides outside and inside the home. Evaluated all homicides, non-firearm homicides and in home homicides. Use homicide records from Detroit Police Department. Analysis using time-series.

Results

There were significant increases in non-firearm homicides (16%) and in homicides occurring in the home (22%) after the law compared to before the law. In contrast, there were no significant increases in firearm homicides (13%) and homicides outside the home (10%) after the law compared to before the law. Ordinance not enforced largely because jails were full.

Study quality and conclusions

The study appears to use valid data and employs ARIMA modeling of time series for analysis.

The authors interpret the lack of a statistically significant increase in firearm homicides and homicides outside the home as showing an effect of the law since these were the target of the law, and homicides inside the home and non-firearm homicides (both not targets of the law) continued to increase. They ascribe the effect of the law to publicity about it since it was not enforced.



Author

Fife, 1989

Study design and target population

Interrupted time series over time period 1974-1986. Population of New Jersey compared to the rest of the U.S.

Intervention

Mandatory minimum prison sentence required for use of firearm in a variety of crimes. Graves amendment, effective 1981.

definition of felony: crimes here murder, manslaughter, aggravated assault, kidnapping, aggravated sexual assault, aggravated criminal sexual assault, robbery, burglary,

Outcomes

Percentage of homicides and suicides that involve firearms over time.

Results

Linear regression used to evaluate proportions of firearm homicides 1974-80 vs 81-86 for N.J. compared to entire US. Overall 3.2% decrease in proportion of firearm homicides in NJ.

No change in proportion of suicides due to firearms in NJ, or for homicides in the rest of the US during the same time period.

Study quality and conclusions

Authors conclude mandatory sentencing reduced homicides due to firearms.

Problems: simplistic analysis-no information on incidence rates, no adjustment for confounding; secular trend for both US and NJ shows proportion of firearm homicides dropped in later period; proportion of firearm homicides much lower in NJ then rest of US



Author

Loftin et al., 1983

Study design and target population

Interrupted time series study design; Detroit, Michigan

Intervention

Michigan’s Felony Firearm Statute (implemented Jan 1, 1977) required 2 year mandatory additional sentence for defendants convicted of possession of a firearm during the commission of a felony.. Accompanying publicity campaign about the law, "One will get you Two"

Outcomes

Length of sentence by original charge, probability of confinement if convicted, probability of conviction, & length of sentence given confinement for Murder, armed robbery, felonious assault and 3 other felonies. In addition, examined homicide, robbery, armed robbery and assault rates.

Results

Law produced no changes in the length of sentence for gun related crimes, the likelihood that persons convicted of violent gun-related crimes would serve time except for felonious assaults. For these assaults, the law may have reduced the likelihood of convicted, but increased the probability and length of conviction.

No evidence of a discernible effect on the level or pattern of violent crime in Detroit.

Study quality and conclusions

No evidence that the law or the publicity campaign which accompanied the law had any effect on violent crime. Law had very narrow scope and penalty not strong enough to be a deterrent.


Author

Loftin and McDowall, 1984

Study design and target population

Interrupted time series design. Population-3 cities in Florida, Miami, Tampa, Jacksonville

Intervention

Florida Felony Firearm Law effective 10/1/75 mandated a 3 year sentence without parole for possession of firearm during commission or attempted commission of 11 different felonies.

Outcomes

Firearm homicide, armed robbery gun assault, non-gun homicide, unarmed robbery, knife assault

Results

Significant decrease in gun homicide found only in Tampa but no reduction found in other two cities. Significant increase in gun assaults in Tampa but no significant increase in other two cities.

Study quality and conclusions

Little evidence that Florida gun law produced any systematic decline in gun crimes in the 3 cities. Authors state scope of law is narrow, applying only to individuals committing armed felonies; also, the additional penalty is less than the felony sentence.


Author

Lucas et al., 1978

Study design and target population

Before/after study design; patients treated for penetrating wounds at Detroit General Hospital, Detroit, Michigan

Intervention

Michigan’s Felony Firearm Statute . Required 2 year mandatory add on sentence for defendants convicted of possession of a firearm in the commission of a felony. Passed Jan 1, 1977

Outcomes

Operations performed for firearm or knife wounds 6 months pre and post legislation.

Results

45% reduction in major surgeries for firearm wounds compared to a 16% reduction for knife wounds. OR=0.63, 0.45-0.68

Study quality and conclusions

Authors conclude legislation responsible for drop in surgery for firearm injuries. No changes in staffing for police, EMS, or in hospital surgical procedures. Limitations: no control group. Comparisons over very short time period; therefore, difficult to determine if sentencing guidelines caused change.

Summary of mandatory sentencing legislation studies

The data available at present give conflicting results as the effectiveness of such laws in decreasing firearm related violent injuries. The analyses are necessarily complex to take into account secular changes in rates of violent crime and firearm related injuries However, these analyses at present only adjust for secular changes and colinearity, but nothing else. There are potential threats to the validity of time series analyses such as other laws, societal changes, and other policies which can influence crime.

Recommendations on mandatory sentencing

At present, the conflicting data, all based on time series analyses, do not allow us to recommend these laws as a strategy which will have a definite effect on injury rates. There may, however, be other compelling reasons to enact such laws.

Recommendations for future research

McDowall and colleagues10

  in 1995 made a good attempt to evaluate shall carry/concealed weapons laws. In 1995 additional states adopted legislation making it easier to obtain concealed weapons permits. These effect of these laws should be evaluated using Poisson regression and time series analyses in order to determine their effect.