The Kansas City (MO) Gun Experiment was a police patrol project that was aimed at reducing gun violence, drive-by shootings, and homicides. For 29 weeks during 1992–93, the Kansas City Police Department (KCPD) focused extra police patrols in gun crime “hot spots” in a targeted area of the city. Extra patrol was provided in rotation by officers from the Central Patrol Division in a pair of two-officer cars. The officers on overtime worked from 7 p.m. to 1 a.m., 7 days a week. They were asked to concentrate on gun detection through proactive patrol, and they were not required to answer other calls for service.
The target area in the gun experiment was patrol beat 144 in the Central Patrol District of Kansas City, MO. The site had the second-highest number of drive-by shootings of any patrol beat in 1991. The target beat was in an 80-by-10-block area that had a homicide rate of 177 per 100,000 persons, almost 20 times the national average (Sherman, Shaw, and Rogan 1995).
The Kansas City Gun Experiment was based on the hypothesis that gun seizures and gun crime are inversely related. In other words, as gun seizures increase, gun crime should decrease. There are two possible mechanisms that can explain this relationship: deterrence and incapacitation. Deterrence theory hypothesizes that if it were to become known that law enforcement is likely to seize guns, illegal gun carriers would be less likely to carry guns in the area. Deterrence theory also suggests that increasing patrol visibility in the area will generally deter all crime. The incapacitation theory suggests that if guns were confiscated from enough potential gun criminals in the area, the criminals would be unable to commit gun crimes (incapacitated)—at least for the time until they obtained a new gun.
The gun experiment was first developed in 1991 from funding provided by the U.S. Department of Justice under the “Weed and Seed” program. The police and academic team that designed the experiment chose the reduction of gun crime as the principal objective of the program because the area had the second-highest number of drive-by shootings of any patrol beat citywide. The federal funds allowed for extra police patrol and overtime.
The KCPD actually implemented three different strategies for increasing gun seizures in beat 144: 1) door-to-door solicitation of anonymous tips; 2) training police to interpret gun-carrying cues in body language; and 3) field interrogations in gun crime hot spots. The extra police patrol in hot spots areas was associated entirely with the third strategy.
The actual techniques used by the officers to locate guns varied widely. They included searches of individuals under arrest on charges other than gun crimes, plain-view searches of cars, and safety frisks of individuals who had been stopped in their cars for traffic violations. The following examples illustrate some of the methods used by officers to seize guns:
- Safety frisk during traffic stop: after pulling someone over for a traffic violation, the officers asked the driver for his/her license. When the driver would lean over to the glove compartment, a bulge may be revealed under the jacket of the left arm. The officer would grab the bulge, feel a hard bulk in the shape of a gun, and reach into the jacket to pull the gun out.
- Plain view: as an officer approached the car he/she had pulled over for a traffic violation, the officer would shine a flashlight onto the floor in the front of the back seat and see a shotgun. After ordering the driver and any passengers out of the car, the officer finds that the shotgun is loaded.
- Search incident to arrest on other charges: after pulling someone over for a traffic violation, the officers asked the driver for his/her license. A computer check reveals that the diver is wanted for a failure to appear on domestic assault charges. The officer would arrest the driver, conduct a search, and find a gun hidden inside the suspect's shirt.
The following is a breakdown of the methods used by the patrol officers to seize guns during the experimental period: 21 percent plain view, 34 percent frisk for safety, and 45 percent search upon arrest.
Some questions may be asked about the methods used by police officers, and often critics of these procedures voice concerns about the rate of false positives and the potential discrimination entailed in responding to certain patterns of situational cues. The U.S. Supreme Court has ruled on the issue of safety frisks in Terry v. Ohio 1968, which allows officers to pat down the outside of the suspect’s clothing to check for guns. However, the Supreme Court has not attempted to articulate the substantive basis for police officers’ suspicions. The court places on the officers the responsibility of articulating a reasonable basis for frisking an individual but implicitly accepts the facts cited by police as reasonable (Sherman, Shaw, and Rogan 1995).
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Sherman and Rogan (1995) found that the Kansas City (MO) Gun Experiment appeared to have a significant effect on gun seizures. The hot spots patrol officers found 29 guns in addition to the 47 guns seized in the target area by other police officers during phase 1, increasing the total guns found in the beat by 65 percent over the previous 6 months and almost tripling the number of guns found in car checks. Overall, there was an increase from 46 guns seized in the target area (beat 144) in the first 6 months of 1992 to 76 seized in the last 6 months. In the comparison beat (beat 242), there was no real change in the number of guns seized during the first 6 months of 1992, compared with the last 6 months of the year.
Looking at the 6-month rates of guns seized per 1,000 residents in the target and the comparison beat, there were 9.9 guns seized in the target area before patrols and 16.8 guns seized during patrols. In the comparison area, there were 10.4 guns seized before patrols and 8.8 guns seized during patrols.
Trends in Gun Crimes
There were 169 gun crimes in the target beat in the 29 weeks before the start of the hot spots patrols, but only 86 gun crimes in the 29 weeks during the phase 1 patrols. This is a 49 percent decline, with 83 fewer gun crimes. This change was statistically significant, using two different models of analysis (t–tests and ARIMA). In the comparison beat, there was a slight increase in gun crimes, from 184 in the 29 weeks before the hot spots patrols to 192 in the 29 weeks during the patrols. However, this change was not statistically significant.
Although gun crime dropped in beat 144, none of the seven neighboring beats observed any significant increase in gun crime. There was some evidence to suggest that the program’s benefits were diffused to two of the adjoining beats. Analyses using the ARIMA model showed significant reductions in gun crimes in beats 141 and 143.
Analysis showed that drive-by shootings declined during the 6-month period when hot spots patrols were active, compared with the periods without patrols, though the difference was not statistically significant. The comparison beat also showed no such difference, and there were no significant differences in the beats surrounding the targeted area.
Homicides were significantly lower in the targeted area during the 6-month program period than in the time period when the patrols were not active. There were no significant differences in homicides across those time periods in the comparison beat or in any of the contiguous beats.
There were no significant changes in the target or the comparison area on total calls for police services; calls about violence, property, or disorder crimes; total offense reports; or prior or violent offenses. The target area hot spot patrols concentrated primarily on guns, and it appears their effects were limited to gun crimes.