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Appendix: Summary of Crackdown Studies

The table below summarizes published studies on crackdowns. Given the frequency and expense of crackdowns, the research is quite limited. The studies listed are not of equal value: some were better implemented than others, some were better evaluated than others. They used a variety of evaluation methods, some stronger than others. Accordingly, you should not use only this table to inform your decision-making about crackdowns. It only supplements the information provided in this guide's main text. Those interested should read the original study reports to better judge the reliability of the findings and conclusions.

Evaluations of police operations are always complicated. Many of the most important things you would want to measure are difficult to measure accurately, such as actual victimizations (as opposed to only those reported), unwitnessed violations, and police officers' discretionary actions. It is equally difficult to determine reliably what factors other than the crackdown might have contributed to the results, and whether and how the problem might have been displaced. Nevertheless, these studies comprise some of the best available information, however imperfect. More and better studies are needed, of course, but in the final analysis, no amount of research knowledge completely substitutes for the good judgment police decision-makers must exercise, taking many factors into account.  






Offenses TargetedJurisdictionYearProject/ Operation NameCrackdown Tactic(s)EvaluationDeemed EffectiveEvidence of Displacement/Diffusion of Benefits/ Residual Deterrence EffectsEvidence of Negative Effect on Police-Community Relations
All crimesNew York City (20 th Precinct)1966Extra police patrol (40% increase)Green (1996) [Full text] and Sherman (1997) [Full text] (both citing Press, 1971)Yes, reduced street crimesYes, spatial displacement to adjacent precincts
All crimesNewark, New Jersey1978-79Newark Foot Patrol ExperimentExtra foot patrolPolice Foundation (1982)No, but had a positive effect on public perceptions of safetyNo, increased citizen satisfaction with police
All crimesDayton, OhioAggressive traffic enforcementWeiss and Freels (1996)No, did not reduce robbery or auto theft or have any measurable effect on traffic crashes
All crimesIndianapolis, Indiana1995Safe Streets ProjectHigh volume of traffic stops in drug market areas; aggressive traffic enforcement; field interviews; street- level drug enforcement; follow-up investigation of arrestees; case- buildingWeiss and McGarrell (1999)Yes, reduced burglary in three out of four districts; reduced robbery in one out of four; reduced auto theft in all four (by 43%, 50%, and 53% in three districts), while the citywide crime rate was climbing
All crimesKansas City, Missouri1974Preventive Patrol ExperimentRandom preventive patrolKelling et al. (1974) NoNo
All crimesNashville, Tennessee1974-75Saturation patrol (four times the normal level, and 30 times the normal level of "slow patrol")Schnelle et al. (1977)Yes, reduced nighttime, but not daytime, burglary; concluded that the crackdown was not cost-effectiveNo spatial displacement
All crimes (specially intended to reduce crimes considered suppressible: burglary; street and commercial robbery; assault; auto theft; thefts from yards, autos, or buildings; DUI; possession of stolen property or weapons; and disorderly conduct)Savannah, Georgia1998Aggressive traffic enforcement, especially of speeding, signal violations, seat belt violations, DUI, and license and registration violations; from 140% to 430% increase above normal levelsJosi, Donahue, and Magnus (2000)Mixed results: there were significant reductions in Part I crimes (mainly burglary and larceny) in three out of four target areas, but there was less evidence of a significant impact on assaults and Part II offenses
All crimes and calls for serviceKansas City, Missouri1991-92Crack House Police Raids ProgramDrug warrant raidsSherman and Rogan (1995)Yes, but the effect was modest; concluded the crackdown was not cost- effectiveYes, some spatial displacement
All crimes and citizen fearNew York City (subways)1984Subway patrol by Guardian Angels (private patrol force)Kenney (1986)No, but there was a short-term reduction in citizen fear
All UCR Index offensesHouston, Texas1994-96Targeted Beat ProgramOvertime to put 655 additional officers in the seven highest crime beats in the city; high-visibility patrol; hot-spot monitoring; zero tolerance; problem-oriented approachesCaeti (1999)Yes, there were significant reductions in UCR Index crimesNo displacement; some diffusion of benefits to adjacent areas
Assault, malicious damage to property, and offensive conductSydney, Australia1992Regular but unpredictable visits to licensed premises to check for breaches of licensing lawsBurns and Coumarelos (1993) [Full text]No
BurglaryUnited Kingdom1995Operation Christmas CrackerRaids; arrests of burglary suspects; seizure of stolen propertyWright and Pease (1997)There was no mention of an evaluation
Burglary (residential)West Yorkshire, England (Boggart Hill area)1995Targeted and intensive enforcement against known burglars, followed by repeat victimization reduction efforts (target hardening, educating elderly potential victims of burglary by deception) and youth outreach programsFarrell, Chenery, and Pease (1998)Yes, there was a significant reduction in burglary and repeat victimizationNo evidence of spatial displacement; some evidence of diffusion of benefits to other types of crime (auto theft)
Disorder-related calls for serviceMinneapolis, Minnesota1988-89Hot Spots Patrol ProgramIntense intermittent patrol at known hot spots (100% increase in patrol time at hot spots)Sherman and Weisburd (1995)Yes, there was a modest effect (25% less disorder at hot spots)
Drug hot spotsJersey City, New Jerseyc. 1992Drug Markets Analysis ProgramIdentification and analysis of drug hot spots; engagement of business owners and citizens in crime control efforts; increased pressure on open-air markets (through drug enforcement, code enforcement, license regulation), maintained by patrolWeisburd and Green (1995)Yes, there were consistent and strong impacts in reducing disorder-related emergency calls for service, but there was no impact on violent or property offensesNo evidence of displacement; some evidence of diffusion of benefits to adjacent areas
Gang-related violenceDallas, Texas1996-97Enforcement of truancy and curfew laws; high- visibility patrol, with lots of stops and frisks by six to eight officers in areas where gangs hung outFritsch, Caeti, and Taylor (1999)Yes, there were significant reductions in gang violenceNo, minimal evidence of displacement
Gun-related crimeIndianapolis, Indiana1997Directed Patrol ProjectTwo alternative interventions: 1) increased traffic enforcement on major arteries, with lots of stops of limited duration (general deterrence strategy); 2) traffic stops of suspected gang members and drug dealers, of longer duration, with more investigation and vehicle searchesWeiss and McGarrell (1999)Yes, the second intervention tactic resulted in significant reductions in gun-related crimes, aggravated assault, and homicide; there were no similar reductions resulting from the first intervention tacticLittle evidence of displacement; no evidence of geographic diffusion of benefits; modest evidence of residual deterrence effects 90 days after interventionNo, evidence of high level of public support both before and after intervention
Gun-related violenceKansas City, Missouri1992-93Gun ProjectIntensive enforcement of gun- carrying laws (Terry stops, searches incident to arrest, car stops and searches, plain-view searches,); door-to-door solicitation of tips; police training to interpret gun-carrying cues; field interviews in known gun crime hot spotsSherman, Shaw, and Rogan (1995)Yes, there was a 49% reduction in gun crimes in the target area during the intervention period, compared with the prior 29-week period; there were declines in both drive-by shootings and homicides; there was no apparent effect on total calls for service, other violence calls, property offenses, or disorder; the community became less fearful of crime and more satisfied with the neighborhoodYes, modest spatial displacement; some evidence of diffusion of benefits to two adjoining beatsNo
Gun-related crimePittsburgh, Pennsylvania1998Firearm Suppression Patrol ProgramExtra dedicated police patrols on high-crime days of week and times of day for 14 weeks; traffic and pedestrian stops and searches; targeting of hot spots and times based on crime analysisCohen and Ludwig (2002) [Full text]Yes, reduced shots fired by 34% and hospital-treated assault gunshot injuries by 71%No evidence of temporal or spatial displacement; residual deterrence effects lasted about two weeksNo, no reported citizen complaints against police
Marijuana cultivationKentucky1982-87Locating, cutting down, and burning marijuana plants; asset seizure and forfeiture; drug enforcementPotter, Gaines, and Holbrook (1990)No (but the methodology limited the findings)Yes
Public disorder (street cruising, loud music, and public drinking)Anonymous jurisdiction1992Liquor license agents issued citations for open containers and other alcohol violations; local police parked police cars at intersections to monitor cruising; lasted for one month in 10-by-12- block area; no media publicityNovak et al. (1999)No (but the methodology limited the findings)
RobberyNew York City (subways)1965Extra police patrols put on subways from 8 PM to 4 AM ; nearly every station and train had a uniformed officer on duty; total transit system police force increased by 250%Chaiken, Lawless, and Stevenson (1974)Yes, minor offenses and felonies declined significantly due to increased patrol, but at substantial extra cost (about $35,000 per felony crime prevented); there was some question as to whether police reporting procedures accounted for some of the claimed reductionNo displacement; residual deterrence effects for eight months
Robbery, burglary, grand theft, petty theft, auto theft, assault/ battery, sex crimes, and malicious mischief/ disturbancesSan Diego, California1973Field Interrogation ProjectField interrogationsBoydstun (1975)Yes (there was some evidence that burglary, petty theft, and malicious mischief/disturbances are the most suppressible)InconclusiveNo
SpeedingConnecticut1955Stiffer sanctions for speeding convictions: 30-day license suspensions for first offense, 60 for second, indefinite for thirdCampbell and Ross (1968)Not definitive; the overall conclusion was that the crackdown was a substantial enforcement effort, but some of its effects were mitigated in practice
Speeding and other traffic problems, crime, and disorder and blightCharlotte, North Carolina1997Saturation patrol by about 30 officers/agents from various agencies; about 10 times the normal level of police activity in the area; traffic unit focused on traffic problems; alcohol agents worked bars; sheriff's deputies supervised inmates doing community service; traffic arrests increased tenfold; police made highly visible arrests in well-traveled parking lot at major intersectionPriest and Carter (2002)Yes, there was some evidence of a modest effect on reported crime; unable to measure the effect on traffic crashes (weak evaluation)
Street drug marketsRichmond, Virginia1999Blitz to BloomRegular patrol supplemented by specialized units (10 times the normal level); field interviews; citations; surveillance; arrest of street drug dealers and buyers; high-visibility presence (including setting up a mobile police command post); code enforcement; cleanup; public works repairs; trimming of foliageSmith (2001)Yes, total reported Part I offenses and violent crime declined significantly (by 92%) during the crackdown period and rates were unchanged in the comparison area; Part I property crimes and calls for service declined, but not significantlyNo spatial displacement of crimes, but significant displacement of calls for service to adjacent areas; some evidence of diffusion of benefits to adjacent areas; residual deterrence effects lasted about six months
Street drug marketsNew York City1988-90Tactical Narcotics Teams (TNTs)Buy-busts and high police visibility in hot spots with high mobility; vehicle seizures and confiscations; initial crackdown operation never lasted longer than 90 days in an area, but maintenance crackdowns occurred as necessary; initiative claimed to incorporate community involvement and interagency collaboration to address drug market conditions, but there is little evidence this occurredSmith et al. (1992)There was a limited impact; there was an immediate benefit, but conditions returned to normal soon after the TNTs left; there were no measurable effects on public perceptions of crime, quality of life, or police-community relations; there was some increase in fear because drug dealing moved indoors to apartment hallways; there were some positive effects in making drug markets less visible in the target blocksYes, some displacement to indoor locationsNo, some evidence community was largely unaware of crackdown in their neighbor-hood; community leaders generally supportive of crackdown
Street drug marketsNew York City ( Lower East Side )1984-86Operation Pressure Point (two smaller Pressure Point operations conducted in subsequent years)240 uniformed officers on foot patrol to disperse crowds; increased arrests; field interviews; warnings and parking tickets; searches; mounted park patrols; canine units to clear buildings; surveillance and buy-busts; anonymous tip lines; raids on dealing locations; asset forfeiture; increased likelihood of conviction and severity of sentences; custodial arrests made instead of citing and releasing; additional responses to address environmental conditionsZimmer (1990) ; Kleiman (1988)Yes, the search time for drugs increased; there was a reduction in heroin-related street activity; there were reductions in selected crime rates: burglary (37%), robbery (47%), grand larceny (32%), and homicide (62%); the neighborhood was revitalized; there was an increased demand for drug treatmentMixed evidence: one study reported no spatial displacement, another reported displacement to other areas in and around city; some evidence of diffusion of benefits to adjacent areasNo, community support levels were high
Street drug marketsTampa, Florida1989-91Quick Uniform Attack on Drugs (QUAD)Observation by four 10-officer teams; arrests for drug dealing, public drinking, etc. (by special unit and patrol officers); short-term undercover work and buy-busts; reverse stings; vehicle seizures; use of confidential informants; code enforcement; neighborhood cleanups; demolition of abandoned buildings; heavy media coverage; visible response to every citizen complaint; encouragement of anonymous complaints, with promises to protect complainants' identities; mobile booking stations to speed up arrests; parked marked units in middle of drug markets; uniformed patrol through the markets; removal of shade covering dealers; use of expedited nuisance abatement procedures; provision of police beeper numbers to citizens so they could feel more assured of anonymity; confiscation of stashed drugs from citizen tips; arrests for loitering for the purpose of drug dealing (and conspicuously posted warning signs); trespass authority arrestsKennedy (1993) [Full text]Yes, visible drug dealing declined significantly, but the study was unable to determine which particular tactics were the most effective; there was some evidence of declines in overall crimes, calls for service, and drug-related homicidesYes, some displacement to indoor locationsNo, evidence of high level of community support from both majority and minority communities
Street drug marketsWashington, D.C.1988Operation Clean SweepHigh-volume arrests for drug dealing and other offensesReuter et al. (1988)No, but there was some evidence that the overall crime rate declined, and the study concluded that local drug crackdowns were worthwhile
Street drug marketsHouston, Texas1988Link Valley Drug Sweep100 officers conducted buy-busts; checkpoints established; door-to-door searches of residences; media publicity; neighborhood cleanups; code enforcementKessler and Duncan (1996)No, there were no significant reductions in overall crime, calls for service, or drug-related crime
Street drug markets (crack)Oakland, California1988-89Special Duty Unit 3Intensive drug enforcement through high- visibility patrol (stopping, questioning, and frisking motorists, bicyclists, and pedestrians); buy-busts (targeted in hot spots); crack house raids; compared with door-to-door interviews with residents to discuss drug problems and a drug hotlineUchida, Forst, and Annan (1992)Mixed results: there was some positive effect on violent crimes but not on burglary and robbery; there were positive effects on citizen perceptions of safety, drug dealing, and police servicesYes, evidence of spatial displacement, but police shifted crackdown to new areasNo
Street drug markets (heroin)Lawrence, Massachusetts1984Lawrence Drug Task ForceSurveillance; informants; informant buys; buy-busts; anonymous drug tip lineKleiman (1988)No, there was some evidence of suppression of the heroin market in one location, but the overall effect on markets and crime was limitedYes, some evidence drug buyers easily shifted to drug market in nearby city
Street drug markets (heroin)Lynn, Massachusetts1983-84Lynn Drug Task ForceFour to six narcotics officers surveilled known drug-dealing locations, questioned buyers and sellers, made arrests for possession, used informants for buy-bust arrests, and executed search warrants on drug houses; hotline for anonymous tips was established and publicizedKleiman (1988)Yes, there was a significant decrease in the volume and flagrancy of the retail heroin market; there was some evidence that heroin use declined; there was an 85% increase in the demand for drug treatment; reported robberies declined by 18.5%, burglaries by 37.5%, and crimes against the person by 66%Unknown if there was displacement to other types of drugs; one year after the crackdown, burglaries stayed down and robberies continued to declineNo, high citizen satisfaction with results
Street drug markets (heroin)Maribyrnong, Australia2000Operation Clean HeartField interviews; high-visibility patrolAitken et al. (2002) [Full text]Yes, but at a high social costYesYes
Street drug markets (heroin)Sydney, Australia1995-97; 2001Buy-busts of dealers and usersMaher and Dixon (2001) [Full text]The study acknowledges some success in disrupting street drug markets, but it focused more on the negative consequences of crackdownsYes, some spatial displacement to indoor locations and other neighbor-hoods
Street drug markets (heroin, crack, marijuana)London2000Operation CrackdownArrests; drug seizuresBest et al. (2001) [Abstract only]NoNo
Street drug markets (powder cocaine and Dilaudid)Birmingham, Alabama1988Operation Caine BreakIntensive drug enforcement (buy-busts, reverse buys, vehicle forfeiture, media coverage of arrests), compared with two other responses: door-to-door surveys of residents about drug problems, and establishment of police substationUchida, Forst, and Annan (1992)Mixed results: there was no measurable reduction in drug trafficking, but there were positive effects on citizen perceptions of police and crime problems; there were some measurable crime reductionsNo
Street drug markets (powder cocaine)Hartford, Connecticut1990COMPASSStreet-level drug enforcement (undercover drug buys, search warrants, buy-busts, reverse stings, surveillance arrests, vehicle safety checks), followed by community revitalizationCaulkins, Larson, and Rich (1993)There was some evidence of effectiveness; there was a dramatic decrease in drive-by shootings; the study concludes that geo-graphically contained areas are more favorable for crackdownsNoNo
Street prostitutionLondon1983-86Intensive enforcement against prostitutes, clients, pimps, and brothel operators, combined with road closuresMatthews (1997) [Full text]Yes, prostitution and serious crime declined significantly; the sense of public safety increased; crime reporting rates increasedNo evidence of spatial displacementNo, actually improved police-community relations
Street prostitutionNew York City (Midtown Manhattan )1993Intensive enforcement of low-level offenses by patrol officers, combined with sanctions of the Midtown Community CourtWeidner (1999)Yes, the incidence and prevalence of street prostitution significantly declined; some stroll areas disappeared almost entirely; there was little evidence that many prostitutes quit the trade, howeverYes, evidence of spatial displacement to outer boroughs; evidence of target, method (prostitutes switched from walking to driving around), and temporal displacement
Street prostitutionNew York City ( Times Square )1983Operation WeekendArrest sweepsEckart (1984)No impact evaluation was reported
Street prostitutionNewport News, Virginia1984Variety of responses in a problem-oriented policing project, including arrests of prostitutesEck and Spelman (1987)Yes, there was a significant reduction in the number of street prostitutes and prostitution-related robberiesNo
Traffic crashesNashville, Tennessee1978Intensive traffic enforcement (compared with normal and below- normal levels)Carr, Schnelle, and Kirchner (1980)No
Violent crime at targeted locationsJersey City, New Jersey1994POP at Violent Places ProjectVariety of responses (28 different ones); aggressive order maintenanceBraga et al. (1999)YesSome spatial displacement of property crimes, but most crimes and calls for service not displaced
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