Can the Effectiveness of Police Stop-and-Frisk Tactics be Enhanced?

The New York Police Department is on track to do 700,000 stop-and-frisks this year, the most in its history. Twelve percent of these stops meet the NYPD’s current criteria for success: An arrest or summons. Put another way, 88% of these stop-and-frisks yield no such result. At least some of those “negative results” from stop-and-frisks have value (e.g., I decided not to put my gun in my belt before I went to settle an argument with another drug dealer because I was afraid a police officer would stop-and-frisk me, and that in fact happened). But some portion of the negative results truly are a dead weight loss, not just in police time but in how they make law-abiding people angry at the police and feed racial hostility more broadly throughout the city.

Modern policing, including in New York City, is all about data monitoring, targets and performance management. Is there a performance management strategy that would increase the benefits and reduce the costs of stop-and-frisks?

Currently, police are rewarded when they make a stop-and-frisk that meets their success criteria (arrest or summons) but are not punished when they make an unnecessary stop-and-frisk. That creates an incentive to do as many stop-and-frisks as possible with a fairly low threshold for suspicion. A better performance management system would instead reward police for the proportion of their stop-and-frisks that were successful

The first challenge for such a system would be deciding what would count as a “successful stop-and-frisk”, because you don’t want it to be something that the officer’s judgment can influence on the spot, like an arrest (one of the current success criteria). Sometimes, the very best thing a cop can do when for example s/he finds a few cans of spray paint on a tagging teenager, both in terms of resource allocation and in terms of improving relationships between cops and citizenry, is to take the contraband and say “I am letting this one pass as a favor to you – go and sin no more.” If the standard of justifiability were the number of arrests per stop-and-frisk, cops would be tempted to make arrests in situations like that when they shouldn’t. A more objective success standard with less perverse potential would be something like calling a stop-and-frisk successful if the suspect turned out to have an outstanding warrant or was carrying an unlicensed firearm.

The second challenge for performance management is figuring out what the right proportion of success should be. As mentioned, good, crime-preventing policing will generate at least some stop-and-frisks in which the person for example chose to leave their unlicensed gun at home, so the performance standard can’t be 100%. In performance management, you don’t have to know the precise numerical goal to know which direction you want to move current practice. If the proportion of stop-and-frisks that were successful by the criteria I have proposed is currently say, 10%, police leaders could simply say that individual officers and precincts which beat that standard would be rewarded, which would move the ball in the proper direction. In itself, this would be a system change in that stop-and-frisks would move in officers’ minds from being an unlimited resource to a budget line item…do I want to spend one of my valuable stop-and-frisks on this guy when I really don’t have very strong suspicions?

The third challenge is to avoid gaming that could occur through under-reporting of the denominator. That is, a group of officers could agree among themselves that they will increase their success rate by doing as many stop-and-frisks as ever, but not reporting the unsuccessful ones as often. One way to get around this problem is to do community audits in the neighborhoods where police work. You would need an independent assessment unit to conduct surveys of people and ask whether they had been stop-and-frisked in the past 30 days (or whatever) as well as whether they had seen someone else stop-and-frisked. The assessor would declare shenanigans when police reports of stop-and-frisk rates were wildly variant from community reports. Mark Kleiman suggested to me that technology could also help, for example videotaping stop-and-frisks much as police already often videotape traffic stops.

Setting up such a performance management system would be a lot of work for the police and would require political leadership, but I actually think the police would benefit as much as would the citizenry at large. Imagine you are a police officer setting off for your morning patrol in two neighborhoods that are similar except that in one, when your colleagues stop-and-frisk a suspect it’s usually successful and in the other it usually isn’t. In which neighborhood would you feel safer? In which would you expect more cooperation from witnesses? And in which would you feel like part of the community versus a distrusted outsider?


  1. Bux says

    The key thing to keep in mind is that crime is far from randomly distributed. For instance, in a famous study in Minneapolis, they found that just 3% of addresses or street corners in Minneapolis generated more than half of the total 911 calls for serious crimes in that city. Let’s say your proposed performance system is implemented. The easy way to improve upon the baseline and increase the ratio of successful stop-and-frisks to total stop-and-frisks is to target stop-and-frisks to high crime blocks or locations. This kind of policing strategy has a name- “Hot Spots Policing”. For deterrence-based policing (or probation/parole supervision) practices to work in the real world, they have to be focused. Otherwise there is too much of a universe and not enough criminal justice resources (e.g., police officers, probation/parole officers) to go around. This is part of the beauty of something like HOPE probation. You are dealing with offenders who already have a track record and are already under the purview of the criminal justice system. Focusing on known criminals is one big help in starting to narrow a deterrence strategy. The next step is to use advances in risk assessment (or use Angela Hawken’s “behavioral triage”) to narrow in further to that sub-set of the known criminals who are likely to continue to repeat at high rates. Of course it helps to have more officers too, which could be done if we could cut the ridiculous amount of money we spend on prison and reinvest it into hiring more officers and/or using better technology.

  2. Curmudgeon says

    Isn’t this exercise a bit like a thought experiment to determine the most efficient way to pile bodies into a mass grave?

    A safe society is one where the police respect basic human and civil liberties by not harassing civilians at random in the name of crime prevention. It’s only morally appropriate to address the question of how to minimize official abuses of human dignity rather than to find ways to make them a more efficient use of public resources.

  3. Brett Bellmore says

    I find myself in agreement with Curmudgeon; 88% of stop and frisks turn up nothing? This isn’t inefficiency, it’s a rampant civil liberties violation!

  4. Bux says

    Curmudgeon and Brett, you can’t underestimate the general deterrent effects of such a strategy though. As Keith points out, not only are stop and frisks intended to lead to direct finds but they are also intended to send a message to would-be criminals that your probability of being caught just went up so don’t even try it. You can’t underestimate the costs (both direct and indirect) of crime either. National crime rates may have gone down (and probably they went down in part precisely because of police practices similar to stop and frisk), by crime is still very costly. I don’t mind getting patted down in an airport if it prevents a terrorist getting on a plane, I don’t mind getting patted down in a high-crime neighborhood if it makes that neighborhood a more safe to walk around in, and I don’t mind getting pulled over at a DUI checkpoint if it makes my drive home late at night all the much more safe. I guess one key distinction is that Curmudgeon claims this is a civil liberties violation because police are “harrassing civilians at random.” The key phrase here is “at random.” As my comments (and I believe Keith’s comments) suggest, we shouldn’t do this at random. We do it in a targeted way. I’m all for careful profiling. Yes, when done randomly this is harrassment. When not done at all it is negligence. So the best option is to do it in a targeted way, recognizing that there will always be false positives.

  5. CharlesWT says

    “As Keith points out, not only are stop and frisks intended to lead to direct finds but they are also intended to send a message to would-be criminals that your probability of being caught just went up so don’t even try it.”

    I.e. the ends justify the means.

  6. Bruce Wilder says

    Bux: “I don’t mind getting patted down in an airport if it prevents a terrorist getting on a plane”

    Having just returned from a lengthy international trip through many airports, I am acutely aware of how much completely irrational authoritarian nonsense gets piled behind your attitude. The practice at airports is very, very costly, and most of it appears very unlikely to be an effective preventive. And, far from making anyone feel more secure, it also appears designed to make everyone deeply afraid and suspicious and/or cynical and annoyed about government through the exercise of petty authority to no purpose.

    Bux seems ready to concede that “at random” is harassment and a violation of civil liberties. But, he endorses the universal and uniform harassment of airport security and DUI checkpoints. Hmmm.

    Rational calculation on the costs of prevention is always a hazardous occupation for the policy analyst, I suspect. But, when you let the imagined benefits of preventing some costly counterfactual to skyrocket, and then count the “false positives” not as a cost or loss, but, rather, as a positive means of achieving an ill-defined goal, things are likely to spin completely out of control in the ol’ cost-benefit analysis.

  7. CharlesWT says

    In New York state, for example, marijuana possession has been decriminalized. You might therefore think that a New Yorker should be able to possess a small amount of pot for his own use without fear of criminal charges. The problem is that it’s still a criminal offense to display pot in public. New York City cops, in the course of “stop and frisk” pat-downs ostensibly aimed at people carrying weapons who may pose a threat, commonly ask people to empty their pockets or bags and then arrest those who, in the process of following a police officer’s order, “display” the pot in their possession. Despite the decriminalization policy, the city has made some 536,000 arrests for marijuana possession, at a cost to taxpayers of at least $500 million, since 1997.
    (page 2)
    How Drug Cops Go Bad: We shouldn’t be surprised when the police officers we ask to break the laws they enforce turn corrupt.

  8. Anomalous says

    Why stop at frisking people who are walking down the street? Police could do a lot to deter crime by searching houses and apartments. Knock on the door and if no one answers, well that’s suspicious so kick the door in. Police will probably find contraband in 12% of residences so that’s a good outcome. Right?

  9. David says

    Stop and frisk has been an effective tool for police since the 1968 case Terry v. Ohio, when the Supreme Court ruled in favor of it. The court agreed with the police that officers face uncertain and dangerous situations on the streets—circumstances that can potentially threaten both law enforcement officers and the public. For this reason, police officers need a set of flexible responses that allow them to react based on the information they possess. Thus, distinctions should be made between a stop and an arrest (or seizure of a person), and between a frisk and a search.

    Under the Terry ruling, a police officer may stop and detain a person based on reasonable suspicion. And, if the police reasonably suspect the person is armed and dangerous, they may also frisk him or her for weapons.

    Reasonable suspicion is defined by a set of factual circumstances that would lead a reasonable police officer to believe criminal activity is occurring. This is different from the probable cause (what a reasonable person would believe) required for an arrest, search, and seizure. If the stop and frisk gives rise to probable cause to believe the detainee has committed a crime, then the police officer should have the power to make a formal arrest and conduct a search of the person.

  10. R. Johnston says

    That 12% figure is almost certainly a dramatic over-representation of success. A stop and frisk that results in a summons or arrest for anything other than a weapons charge is a failure. A stop and frisk that results in a summons or arrest on a weapons charge that gets dismissed is a failure. I’d bet that the overwhelming majority of that 12% figure is summonses or arrests for nonviolent drug or drug paraphernalia possession charges, something the linked article carefully avoids mention of.

  11. Bruce Wilder says

    David, can a police officer, without probable cause, lawfully direct that you empty your pockets or open the trunk of your car?

  12. CharlesWT says

    The NYPD, rarely shy about touting success, does not promote its record-breaking crackdown on small-time marijuana possession. The report identifies incentives for the NYPD to focus on marijuana arrests. For instance, the arrests provide police officers a relatively safe and easy way to demonstrate productivity, especially in an organization such as the NYPD that heavily relies on statistics to measure effectiveness. Among other benefits, the arrests also help officers accrue overtime pay. Supervisors use marijuana arrests to generate arrest records, facilitate supervision of police activities and show that their officers are productive.

    The arrests also succeed in dramatically expanding the NYPD’s vast database of New Yorkers’ personal information. Each marijuana arrest brings a new set of fingerprints and photos into the NYPD’s extensive system.

    NYC Marijuana Possession Arrests Skyrocket, Illustrate NYPD Racial Bias, New Report Shows (April 29, 2008)