Understanding the Impact of Police Stops

Compiled from Criminological Highlights by Anthony N. Doob and Rosemary Gartner (University of Toronto)

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Table of contents:

  1. Introduction
  2. Evaluating the evidence on ‘police crackdowns’
  3. The police and crime: Hotspots and intensive police activities
  4. “Broken windows” policing and proactive police stops and searches: Effects on crime.
  5. Police stops: Race
  6. A related issue: Warnings
  7. The importance of fair treatment by the police
  8. Citizens’ views of the police.
  9. Ensuring cooperation with the police
  10. The effects of contact with the criminal justice system
  11. Conclusion
  12. Highlights


Imagine that technology existed such that the police could, electronically, identify and track everyone and every motor vehicle in the city and that this information were stored electronically and available to the police, as required, for solving crime. Even if such information was not admissible as evidence, one could easily see its possible value in solving crime. If a home were broken into, one only would have to search a data base to find out who had been in the neighbourhood. If a pedestrian were hit by a car that did not remain at the scene of the accident, one would only need to see what vehicles had been at that scene around the time of the accident to narrow down the possible suspects considerably. If a person were found to be using or in possession of drugs, one would only need to see whom that person had been in close contact with in recent times to identify a fairly small group of suspects as the source of those drugs. If a person were thought to be a member of a gang, it would be easy to find out whom that person associated with on a regular basis.

We don’t live in such a society. Obviously the information that the police have about the non-criminal activities of ordinary citizens is much more limited than that described in the previous paragraph. But what if it turned out we did live in the world described in the previous paragraph and people suddenly expressed the desire no longer to live in a world with constant and complete police scrutiny of their ordinary activities? One could imagine the suggestion would be made that not allowing police the kind of surveillance described in the previous paragraph would limit their ability to solve crime.

We raise this hypothetical scenario for a particular reason: There is no point in arguing whether complete or highly detailed information about the day-to-day movements or meetings that Canadians have might be useful to the police in solving crime. At a more mundane level, we see on an almost daily basis that footage from ‘security’ cameras is now routinely used to solve crime in a manner not too different from that described above.

Our second example comes closer to the issue of police stops. Imagine that there were no controls whatsoever on the power of the police to stop pedestrians and motorists and ask them to identify themselves. Even if, in law, citizens were not required to identify  themselves or to answer any questions, one could argue that maintaining whatever information was obtained could be useful if a crime took place in that neighbourhood or someone associated with the person who had been stopped was suspected of some wrongdoing. That this information could potentially be useful is not the  point.  The question that needs to be raised in both of these examples is a much more complex one: What might be the ‘costs’ and ‘benefits’ to society of these kinds of data gathering programs?
Even these two hypothetical scenarios are missing something crucial: comparison groups. The question, in most public policy areas, is not whether there are some successful outcomes from a particular procedure, but whether there are better outcomes overall than there might be under some other procedure. For example, in each of the hypothetical scenarios described above, it might be that deployment of resources in some quite different way or a decision to address some quite different problem would serve the community better than the scenarios described. Or such procedures as described earlier might help solve crime but would lessen cooperation with the police on important matters. Comparison groups or procedures typically are not employed adequately when assessing possible policy choices, but in reality the need for a ‘comparison’ is usually important. In a discussion about police equipment (e.g., body worn cameras), not only might one want to know whether they affect police or citizen behaviour (implying a comparison with how police or citizens behave without the device), but a serious policy analysis should include an analysis of alternative uses of the resources that would be required for the purchase and use of the devices.

An example of the inappropriate use of implied comparisons is when changes in police strength or police tactics are implemented after an unusual (e.g., serious, violent) incident. When police, understandably, change their approach to policing a neighbourhood that experienced an unusual incident or high concentration of serious incidents, they sometimes infer that any subsequent return to ‘normal’ levels of crime is ‘caused’ by changes they made in their presence in the neighbourhood. Without adequate comparison areas (e.g., areas that experienced a ‘spike’ that did not result in changes in policing), such causal inferences simply aren’t defensible.

The issues become more complex when one moves closer to reality. One fact about crime that noone questions is that it is not evenly (or even randomly) distributed across people, groups of people, or neighbourhoods in our society. Young males, for example, are disproportionately more likely to be involved in a variety of different kinds of crime than other people. People who live in certain kinds of neighbourhoods are more likely to commit offences than people in other neighbourhoods. But some neighbourhoods themselves appear to have characteristics that make them more likely to be the sites for crime above and beyond the characteristics of the individuals who live in them (see, for example, the research summaries provided on pages B1 and B2: 1-2-2; 6-2-7) (Hereafter, we will simply cite the page number in Part B of this report for the full summary from Criminological Highlights. The numbers that follow are the Criminological Highlights reference (volume, issue number, item number). The “Part B” page numbers are at the bottom right of each page.). In this context, a policing perspective that did not consider any other concerns could justify focusing surveillance resources on certain neighbourhoods or types of people (e.g., young males). The problem is that there almost always are other concerns, and concerns that could easily have the effect of undermining the crime control goal of proactive policing activities, such as police stops.

This report examines some of the more reliable research that has been carried out on issues broadly related to ‘street stops’ of ordinary citizens. It makes the assumption that stops can have more than one effect and that some of these effects might, broadly speaking, be favourable and others unfavourable. Hence this report is more than an attempt to answer  the question of whether street stops have a short term effect on local crime.

We are not claiming to provide an exhaustive review of the literature that summarizes all of the research on issues related to street stops. Were we to do so, we would spend considerable resources reviewing and discarding inadequate research papers. Instead we are relying on Criminological Highlights, a research information service, produced by the Centre for Criminology and Sociolegal Studies of the University of Toronto.2 The papers summarized  in this information service not only have been reviewed by reputable social science journals, but also by our editorial board (currently of about 11 people), which has read and evaluated each paper that is summarized in Criminological Highlights. The one page summaries of articles we cite are attached to this report and are an integral part of it. Most importantly, these summaries make it easy for readers to evaluate the information on which our conclusions are based.

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Evaluating the evidence on ‘police crackdowns’

One of the difficulties in separating effective policing strategies from ineffective ones is that during the time that the most experimentation on these issues was carried out – starting in the early 1990s – crime was decreasing in many areas of the US, Canada, and in some other countries. Hence, where the comparison was ‘what was happening before the change in police activities,’ almost any policing strategies appeared to be effective. Perhaps the most famous example of this was in New York City where the police chief (William Bratton) took credit for a drop in crime, suggesting that aggressive policing of disorder was responsible for a more than 50% decrease in homicides. His argument would have been more persuasive if relatively comparable drops in crime had not occurred in a number of US cities that did not change their policing strategies (B3:1-4-5). But in addition, the overall pattern of the decreases in homicide (e.g., similar decreases in firearms homicides for men and women; decreases in non-firearm homicides for all age groups) do not fit the conclusion that it was aggressive policing per se that was responsible for the drop, though it is possible that massive attempts to keep firearms off the street and out of public places could have had some impact, at least on firearms homicides (B4:2-5-7).

A careful analysis of the changes in policing strategies and crime rates that took place in three cities illustrates this problem. All three cities had police interventions. All three cities also experienced decreases in their homicide rates. A careful analysis of the effects in two cities (New York and Boston), which compared their crime trends with those of 95 other cities, showed no consistent effects of the interventions. Only in Richmond, Virginia, was there some evidence that the police intervention had an impact. However, one simple fact makes that conclusion problematic: Richmond’s homicide rate varied from about 80 to 36 homicides per 100,000 residents; the 95 “comparison cities” varied from about 20 to 13. Clearly the “comparisons cities” were much safer that Richmond to begin with and so could not be considered to be appropriate comparisons (B5:7-5-2).

The need, in research on issues such as the effectiveness of police interventions, is not just for any comparison group. What is needed is a comparison city (or other location) that is similar in all ways other than the fact that an intervention took place.

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The police and crime: Hotspots and intensive police activities

Nobody seriously questions the importance of the police as a key agency in the criminal justice system. The disagreements that arise about the importance of the police in  preventing crime arise largely in discussions about the degree to which the police can affect the amount of crime that occurs in society and whether particular broad approaches to policing can be relied on to reduce crime.
Some issues aren’t necessary to discuss. For example, the issue of what crime rates would look like if there were no police (e.g., if a strike were to take place) has little bearing on the issue of what effect variations in the normal activities or concentration of police might have on crime. At the same time, it is worth remembering that police services are not the only important determinant of crime, or of variation in crime over time. Various scholars have noted that police services are not well placed to stop a good deal of crime. The apprehension, and contributions to the successful prosecution, of those who offend is important in and of itself. But other organizations are also involved in crime prevention.  For example, one of the apparent ‘crime prevention’ successes in recent years – reduction in auto thefts – relates more to engineering and design than to traditional policing (see B6:7-5- 1, and B7:16-1-8).

This is not to say that the police cannot affect crime rates in a neighbourhood. There is sufficient research on the policing of so-called ‘hot spots’ – locations in which high rates of crime take place over an extended period of time – to know that ‘hot spot’ policing can reduce crime. Fortunately, there is sufficient evidence on this issue that it is plausible to  draw certain (at least tentative) conclusions.

The context for one study was concern about firearms misuse in Pittsburgh, Pennsylvania.  In response to this concern, concentrations of police were increased dramatically (20% to 50%) in local areas in which there was evidence of illegal carrying of firearms in public places. The increased police presence occurred at times and locations that had been high in crime. These newly deployed police did not respond to normal calls for service but, instead, concentrated on ‘stopping and talking’ to people whom they considered to be at high risk for carrying firearms. Essentially, visible police presence increased dramatically. Using “assault related gunshot injuries” and reports of “shots fired” as measures of success, it appeared that this high concentration of police in small local areas was successful in suppressing firearms violations while the police were there.  Perhaps not surprisingly, however, the effectiveness of the strategy seemed to be limited to the times and locations in which the police concentration was high (B8:7-6-1).

A very similar result (in the same city) was found for concentrated enforcement of drug laws in locations that the police had identified as ‘nuisance bars’ where illegal drug sales were taking place.  Although the results are somewhat complex, essentially the ‘positive’ impact  of concentrated police action was quite local (suppressing drug sales in the establishment that was targeted and the immediate area only) and, more importantly, the reduction in illegal drug activity did not last long after enforcement was reduced to normal levels (B9:6-3-5).

Sometimes there is a conflict between what the police say about a targeted program and what systematic evidence demonstrates. An effort by London, England, police to interrupt drug trafficking by arresting those selling drugs on the street provides such an illustration. The goal had been to make drug purchases more difficult and more expensive. Though the police described it as a “spectacular success”, systematic evidence collected from drug users suggests that this wasn’t the case (B10: 4-5-3).

These findings are similar to the impact of intensive foot patrols on crime. In Philadelphia, in 2009, 120 ‘hotspots’ for serious crime (homicide, aggravated assaults, robberies) were identified. In 60 of them intensive patrols were instituted; the other 60 locations served as controls. The locations that got the intensive patrols were randomly assigned; hence prior to the intervention it is reasonable to assume that locations the received intensive patrols were similar to those that did not. A careful analysis of the project demonstrated that there was approximately one crime averted in the areas subjected to intensive patrols for every 2174 person-hours of patrol (B11:12-3-3). However, these effects were short lived.  After the  high concentration patrols stopped, the effects disappeared (B12:13-3-2).

The mechanism for these effects appears to be fairly simple: People do not offend when they perceive there is a high likelihood of being apprehended by the police. However, even these effects seem to be more pronounced when the police concentrate their ‘suppression’ efforts on specific named individuals who are thought to be involved in crime (B13:15-2-3). Presumably, focusing activities that make the presence of police salient to those most likely to commit offences is, simply, more efficient. In another study, it was shown that high density patrols in which police officers engaged in various activities, such as checks of buildings, vehicles, and pedestrians, as well as other activities that made their presence known, had some favourable impacts on certain crimes. What was a  bit  surprising, however, is that the effects were limited to reducing non-domestic firearms assaults (and not, for example, firearms robberies). It appeared that focusing police attention on arrests and checking occupied vehicles accounted for the crime reducing effect. One important aspect  of this study was that it dealt with very small geographic areas (each area had an average of 128 residents). These geographic areas were randomly assigned to receive policing as usual, high density (ordinary) policing, or high density ‘active’ policing. Without the control conditions, it would have been impossible to determine what the effects really were since firearms crimes decreased in all areas (B14:14-5-3).

Clearly under some circumstances high visibility active police presence in a community can reduce crime. One obvious mechanism, already mentioned, is that such activities increase the perceived likelihood of apprehension for those who might otherwise commit offences. Police enforcement programs for traffic offences that are visible to ordinary drivers – often because their implementation is combined with media campaigns – can be effective in reducing serious traffic accidents in large part because people change their behaviour if they perceive a high likelihood of apprehension (B15:7-6-7). It has been suggested, more generally, that police should, in their crime control efforts, focus on activities that increase the perceived likelihood of apprehension (B16:11-6-1).

It is important, however, to note that simply increasing the number of police officers in a jurisdiction does not necessarily lead to a decrease in crime. During the period 1995-2000, the US Department of Justice gave some local police services funds for the hiring of more police officers. Since funds were not distributed equally across cities, it was possible to see whether the new funds had a consistent impact on crime. There were no consistent effects (B17:8-6-6), perhaps because the size of the increases in police was, on average, quite small.

The lesson seems to be that ‘more’ is not necessarily better; resources need to be targeted to activities that can be demonstrated to have favourable impacts.

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“Broken windows” policing and proactive police stops and searches: Effects on crime.  

In considering whether ‘disorder’ in neighbourhoods should be viewed as a ‘crime problem’, probably the first thing to assess is whether ‘neighbourhood disorder’ is causally linked to crime. One study (B18: 3-3-1), carried out in Chicago, examined this directly.

Social disorder (e.g., adults loitering or congregating in public places, public alcohol consumption, drug selling) and physical disorder (e.g., presence of garbage or litter, graffiti, abandoned cars) were quite highly correlated. Not surprisingly, “disordered” neighbourhoods were poorer, more likely to have high concentrations of immigrants, and lower in “collective efficacy” (i.e., the willingness of neighbours to “do something” in response to problems, trust in one’s neighbours, neighbourhood social cohesion, etc.). Collective efficacy has been found in previous studies to be an important predictor of neighbourhood crime above and beyond characteristics of the individuals in the neighbourhood.

The most important findings, however, were that measures of social and physical disorder (what some have termed “broken windows”) were not related to personal violence and household burglary (assessed by victimization measures) once characteristics of the neighbourhood (e.g., collective efficacy, mixed land use) were controlled for. “The results are consistent and point to a spurious association of disorder with predatory crime” (p. 627. Page references for quotes are the page in the original article where the quote appeared. The citation can be found in the cited Criminological Highlights summary in Part B.).
When examining officially recorded crime, “disorder” once again disappeared as a predictor of homicide and burglary once measures of collective efficacy and prior crime rates were controlled for. “The key result is that the influences of structural characteristics and collective efficacy on burglary, robbery, and homicide are not mediated by neighbourhood disorder” (p. 629). The exception was officially recorded measures of robbery where there was a relationship with disorder even after controlling for other factors. Whether this is due to a “complex feedback loop” (p. 637) or an artifact of official data (e.g., “citizen calls to the police or police accuracy in recording robberies is greater in areas perceived to be high in disorder” --p. 638) is not clear.

The authors of this study concluded that: “The active ingredients in crime seem to be structural disadvantage and attenuated collective efficacy more than disorder. Attacking public disorder through police tactics may thus be a politically popular but perhaps analytically weak strategy to reduce crime, mainly because such a strategy leaves the common origins of both [disorder and crime], but especially [crime] untouched. A more subtle approach suggested by this article would look to how informal but collective efforts among residents to stem disorder may provide unanticipated benefits for increasing collective efficacy... in the long run lowering crime” (p. 638).

In this context, then, it is not surprising that attempts to deal with serious crime by focusing on those responsible for minor disorder (e.g., those using drugs in public) are not likely to be effective. One study (B-19: 8-5-8) noted that if the police ‘theory’ is that the way to deal  with important crime is to crack down on less serious matters, such as using marijuana in public view, then the police can easily (though not necessarily purposefully) create findings that make it seem that a crackdown was effective. This study found that the locations with the biggest drop in crime were those with the largest increases in crime in the period immediately before marijuana arrests had been instituted as a crime control technique. The police, presumably believing that public order arrests would reduce crime, focused on those locations with the largest increases in recent years. In fact, the precincts with the largest violent crime decline after the public order arrests started were those that had the largest increases in crime in earlier years and, coincidentally, the largest ‘crack down’ on using marijuana in public places. When the violent crime rate prior to the marijuana crackdown or the change in violent crime prior to the marijuana arrest policy is taken into account, those locations with the most marijuana arrests had higher, not lower, levels of violent crime.
These findings are very similar to another study (B20: 8-4-1) that demonstrated the necessity of controlling adequately for pre-existing changes in crime rates. (Essentially what we are referring to here is a phenomenon sometimes called “regression to the mean” which refers to circumstances where, when an observation that is first made is extreme, it will ‘naturally’ tend to be closer to the mean on a subsequent observation. A mundane example might be that if it is unusually cold on Day 1, it is more likely that the Day 2 temperature will be warmer (closer to the mean) on Day 2.)

Not surprisingly, the research on the impact of ‘order maintenance policing’ – the aggressive targeting of minor problems (vagrancy, loitering, littering, prostitution, etc. – is not entirely consistent across studies. One study (B21:9-1-2) suggested that about 4% of the decline in homicide and robbery in New York between 1988 and 2001 was due to variation in the implementation of order maintenance policing. The other 96% of the decline was, presumably, due to other factors. It is possible, however, that the precincts in which order maintenance policing was implemented most aggressively also implemented other policies related to crime. In any case, it is almost certainly safe to conclude that variation in this form of aggressive policing was not responsible for much of the drop in crime in New York City during this period.

One theory used to justify ‘order maintenance policing’ is that frequent police stops and ‘zero tolerance’ policies for minor infractions send a message to the community that crime  of any sort won’t be tolerated. Unfortunately, it doesn’t seem to be that simple. One study (B22:4-5-4), for example, found that targeting aggressive enforcement at minor infractions might have increased compliance with these minor matters, but had little measurable impact on real crime. The authors of the paper concluded that “[q]uality of life initiatives are often employed without the benefit of careful problem identification or analysis, without any  effort to identify underlying conditions and causes, and without careful consideration of a wide range of possible alternatives” (p. 880).

One study (B23:15-5-2) that looked at 28 relatively high quality studies of ‘policing disorder interventions’ found very small effects on crime, but all of the favourable (crime reducing) effects were attributable to those studies involving community problem solving. Those programs that attempted to carry out ‘aggressive order maintenance’ programs (e.g., focusing on minor forms of disorder such as public drunkenness, prostitution, vandalism, disorderly youth, or traditional arresting of those thought to be gang members) did not show statistically significant effects. The authors concluded that “When considering a policing disorder approach, police departments should adopt a ‘community co-production model’ rather than drift toward a zero-tolerance policing model, which focuses on a subset of social incivilities….” (p. 581). This latter approach appears to be ineffective. 
“Stop, question, and frisk” (SQF) approaches to order maintenance have been criticised on a number of grounds, including that they are racially targeted. In New York City, for example, it was found (B24:14-5-4) that there were 26 stops of Black people per 100 Black residents, compared to 3 stops of White people per 100 White people. The results reported in this study regarding crime, however, were less clear. The results “show few significant effects of several ‘stop, question and frisk’ (SQF) measures on precinct robbery and burglary rates” (p.
116) and the significant results did not hold across crimes or type of analyses. A cautious conclusion, according to the authors, might be that one “cannot conclude from the current investigation that SQF has no impact on crime in New York. But we can be more certain that, if there is an impact, it is so localized and dissipates so rapidly that it fails to register in annual precinct crime rates, much less the decade-long citywide crime reductions that public officials have attributed to the policy. If SQF is effective, but its effects are highly focused and fleeting, policy-makers must decide whether expansions in a policy that already produces nearly 700,000 police stops a year are warranted, especially given the ongoing controversy regarding the disproportionate impact of SQF on racial and ethnic minorities and the possibility that it reduces police legitimacy, which may erode its crime-reduction effects over the long term” (p. 117-118).

Another study (B25:15-6-3) that looked in detail at SQF approaches in New York City found that “in the peak years of SQFs in NYC, the almost 700,000 SQFs would lead to only a 2% decline in crime” (p. 47). Attributing the decline in crime solely to SQF is problematic in  that it is impossible to separate out the effect of SQF on crime from the mere presence of police. In addition, attributing this modest drop in crime to SQF ignores the “degree that SQFs are coupled with other policing strategies” (p. 49). Specifically, “[i]n light of research findings on the effectiveness of directed patrol, the prolonged presence of police in a crime hot spot might very well be the active ingredient of SQFs, as opposed to anything that the police were doing” (p. 61). As one commentator noted “the efficacy of the SQF tactic, at least from the standpoint of marginal deterrence, is considerably more ambiguous than its advocates might like to admit” (p. 62). Finally, even if there is a small effect, it is impossible to know whether this effect relates only to certain types of SQFs (e.g., those involving actual offenders).

Changes in policing do not necessarily have simple effects. For example, the previous study (B25: 15-6-3) noted that “The aggressive use of SQFs could erode citizens’ willingness to report crime to, or to cooperate in investigation or intelligence gathering with, the police. In a recent survey… young respondents who were stopped more frequently reported less willingness to report crimes even when they were the crime victims” (p. 63). Even if it could be shown that the apparent effects of SQFs on crime are due to SQFs and not some other correlated factor, “[t]he question is whether this approach [SQFs] is the best one for crime prevention at hot spots and whether its benefits are greater than its potential negative impacts on citizen evaluations of police legitimacy” (p. 50). But in addition, one study (B26:10-3-4) found that intensive policing of some neighbourhoods in which the police engaged in crackdowns on street-level disorder increased, rather than decreased, the  likelihood that people would feel unsafe in their neighbourhoods.

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Police stops: Race

It would be almost impossible, and inappropriate, to discuss police stops of citizens and not talk about race. We hasten to point out, however, that we do not think that the issue of race is the only one relevant to concerns about police stops. Nevertheless, it is hardly controversial to suggest that race is an important factor to be concerned about.

One of the reasons that we should be concerned about the relationship of race to the likelihood of being stopped is that the perception that racial profiling takes place leads to inferences by many citizens that the police are acting in an illegitimate fashion (B27:7-1-4).

A number of different studies have attempted to determine whether police stops (and searches) disproportionately target members of certain racialized groups. One Canadian study (B28: 12-5-5), using a nationally representative survey of 4,164 youths, found that youths who were Black, Arab/Middle Eastern or Aboriginal were more likely to be questioned by the police than other youths (White or East/South Asian) even when other potentially relevant factors were controlled for. These ‘other factors’ included such things as staying out late or low income. But in addition, controlling for three forms of self-reported delinquency did not reduce the higher likelihood that youths who were Black/Aboriginal/Arab/Middle Eastern would be stopped. More interesting, perhaps, is the finding that among youths who reported involvement in violence in the previous year, those who were Black/Aboriginal/Arab/Middle Eastern were no more likely to be stopped by police than other youth. However, there was a sizable difference in level of police contact  for youths who had not been involved in violent crime in the previous year: 28.5% of Black/Aboriginal/Arab/Middle Eastern youths had contact with the police compared to only 10.1% of the other youths. The overall finding, and the fact that the effect was due largely to differential treatment of non-violent youths, lends some support to the conclusion that the difference in treatment of the two groups relates to racial targeting by the police.

These findings are fairly similar to those from a representative survey of Toronto high school students (B29: 16-3-4), which found that Black high school students were considerably more likely to be stopped at least once than were white high school students (63% vs. 41%). 30% of high school youths of other races reported being stopped at least once. Other variables also predicted stops and/or searches including social class, the level of engagement in public activities on the street, involvement in partying, frequency of driving, involvement in illegal activities, and membership in gangs. However, while these factors independently predicted stops and searches, being Black had an impact above and beyond these factors for Toronto high school students. This study also included a sample of ‘street youths’ – those living on the street or in a shelter. For the street youths, race did not predict stops or searches. 66% of the street youths met the criteria set in the study for being ‘highly involved in illegal activities.’ It would seem that “high criminality exposes people of all races to equal levels of police scrutiny” (p. 341). Hence, street youths, as a group, had a very high likelihood of being stopped and searched no matter what their race. At the other end of the spectrum, however, for youths who reported no involvement in illegal activities, 4% of the White youths and 27% of the Black youths reported multiple police stops. It seems that “good behaviour does not protect Black youth from police contact to the same extent that it protects White youth” (p. 340).

There have been a number of studies in various countries about the differential treatment of people of different races by the police. As various authors have pointed out, (e.g., B30: 7-2- 2), determining what the ‘expected’ rate of stops for any group is not simple. But in addition, the vulnerability of different groups to being stopped seems to vary across areas. People who appear to be ‘out of place’ (e.g., Black motorists in predominantly white areas) appear to be particularly likely to be stopped (B31:5-4-2).

There are even more complex findings on what happens after citizens are stopped by the police. A study (B32:13-2-8) in St. Louis, Missouri, found that after a stop of a motorist for  a traffic violation, searches were most likely to take place when White officers stopped Black drivers (searches took place in 8.2% of stops) and were least likely when Black officers stopped White drivers (1.5% of stops). Between these two extremes, White officers were more likely to search White drivers (5.1% of stops) than were Black officers who stopped Black drivers (3.9% of stops). But in addition, this pattern varied according to the racial makeup of the neighbourhood in which the stop took place.

The consequences of being stopped also appear to vary across race. One study (B33: 6-4-4) based on a survey of US residents found that Blacks and Hispanics who are stopped were more likely to be subject to police actions (such as being ticketed, arrested or being subject to the use of force). However, Blacks and Hispanics were less likely to be found to be involved in any criminal wrongdoing, suggesting, perhaps, that “targeting drivers solely or even partially on the basis of their race/ethnicity is not an effective, efficient, or responsible policing strategy at the national level [in the U.S.]” (p.82). These findings are similar to those of another study (B34: 12-1-7) which summarized the findings from 27 independent high quality studies of what happens to suspects when they come in contact with the police.
Depending on exactly what outcome was considered, between 19 and 24 of the 27 studies show effects supporting the conclusion that minorities are more likely to be arrested than whites. Pooling across the 27 studies there was a significant effect of race. On average the arrest rate for whites was about 20%; for minorities it was about 26%. Studies varied, of course, on how adequately they controlled for legally relevant factors. However, the adequacy of the controls for legally relevant factors was not related to the race effect: Even in the best studies, Blacks were more likely to be arrested than Whites. Similarly, those studies that attempted to control for the demeanour of the suspect showed race effects on the outcome of police decisions as large as those that did not.

In this context, then, it is not surprising that Blacks are more likely than others to perceive that policing decisions are made, in part, along racial lines (B35: 3-1-3).

Importantly, one does need to consider that even stops that don’t lead to any formal criminal justice consequences can have negative impacts on people. It appears (B36:14-5-2) that people become less engaged with their communities if they are subject to what might be considered ‘unproductive’ police stops.

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A related issue: Warnings

Although warnings given to those stopped and questioned by police are not central to the question about the ‘impact’ of police stops, there is a growing literature on this topic. A question underlying much of this research is a simple one: Do warnings effectively convey to people what they legally do and do not have to do? Said differently, if people agree to answer questions, or agree to being identified and searched after being warned about potential consequences, is it safe to assume that they understand the warning? We won’t go into this literature in great detail but we think it should be considered in when thinking about the effects of police stops.

The first finding – and one that may help explain other findings from this line of research -- is that “warnings” given to suspects by the police do not seem to affect the ability of an accused person to resist giving a confession (B37: 5-5-5). Another (US) study (B38: 13-4-2) similarly found that warnings do little to protect accused youths from the consequences of making statements.

More relevant are two Canadian studies that examined whether warnings given to adults (B- 39: 11-3-7) or to youths (B40: 15-6-7) are adequately understood by those who receive the warning from the police. The conclusion of these two studies is simple: Warnings are not well understood by either adults or youths.
The study of warnings given to Canadian youths concluded that perhaps because warnings are often long and written in language that is difficult for youths to understand, it is it not surprising that young people do not fully understand the warnings that are normally used by police. “Also of importance was the fact that participants [who were read the warnings used by their local police] reported high levels of confidence in how much they understood and almost always confirmed that they understood the rights that were presented – despite the overall low level of comprehension. This finding suggests that simply asking youths whether they understood the rights is not a useful procedure for ensuring that youths actually understand their rights” (p. 821). But, in addition, other research suggests that even if they understand the ‘words’, youths may not be able to resist the pressures to make statements to the police.

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The importance of fair treatment by the police

The view that fair treatment of ordinary citizens by the police is important is, we think, widely shared. Society asks police to do certain jobs and grants the police certain unusual powers (e.g., the use of force) but in return expects fair treatment. There is considerable evidence that procedurally fair treatment by the police is important in motivating ordinary people to cooperate with the police. Furthermore, procedural justice appears to be just as important for youths as it is for adults (B41: 15-1-5).

But there are other important reasons for wanting fair treatment from the police, most notably that unfair treatment by the police leads people to question the legitimacy of the police and their right to use force. One study (B42: 15-3-2) found that perceptions of the legitimacy of the police are correlated with perceptions that the police act in a procedurally fair manner. Furthermore, it showed that those who see the police as acting with legitimacy are less likely to support ordinary people’s use of violence for personal protection, to resolve disputes, or to achieve political goals.

Another (Australian) study (B43:15-4-3) found that being treated in a courteous, friendly way and being given an explanation for a stop by the police was “consistently important for influencing both emotional reactions and compliance [with the law and the police]…. By engaging with the public in a polite, respectful, and empathetic manner, police officers will be able to reduce negative sentiments and emotion directed at them, thereby increasing people’s willingness to comply with them both immediately and in the future” (p. 269). “If the police wish to be able to effectively manage citizen behaviour and promote compliance with the law, the findings… suggest that they ought to treat people with procedural justice” (p. 270).
There also is evidence (B44: 12-5-6) that the degree of “legal cynicism” in a neighbourhood – lack of support for the legitimacy of laws and lack of confidence in the police – is related to crime rates in the neighbourhood. Simply put, if the law is unavailable because citizens do not trust the police, people may resolve their grievances in their own ways, which may include violence.

One longitudinal study (B45:16-3-7) of 689 African American youths noted that “For the state to secure voluntary compliance from the public, it is necessary for it to be perceived as morally credible” (p. 520). It found that the legitimacy of the state in the eyes of young  Black Americans is undermined most dramatically when negative interactions with the police occur to those who live in neighbourhoods with high levels of legal cynicism. These results are independent of individuals’ record of offending, arrests or other criminal justice contact.

How the police behave toward citizens, then, can affect crime. A study of officially recognized police misconduct in New York City (B46:7-6-3) found that in highly disadvantaged neighbourhoods, the level of police misconduct predicted the violent crime rate. “In [the poorest] communities, residents may feel the most marginalized and socially dislocated and they may respond the most adversely to (real or apparent) violations of procedural justice norms by the police, who represent the most visible agents of official social control … These findings suggest the importance of police departments meeting procedural justice expectations, specifically in extremely disadvantaged communities” (p. 492).

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Citizens’ views of the police.

The quality of the treatment that people receive affects people’s views of the justice system. In fact, it appears that the quality of the treatment – as opposed to factors like the ability of the police to reduce crime – is most important in understanding people’s views of the justice system (B47:4-4-1).

Statistics Canada survey data suggest that, in general, Canadians have quite positive views of the police. A study (Sprott, Jane B. and Anthony N. Doob (2014). Confidence in the Police: Variation Across Groups Classified  as Visible Minorities. Canadian Journal of Criminology and Criminal Justice, 56(3), 367-379._ using the 2009 Statistics Canada General Social Survey data that looked at urban Ontario residents’ views of the police found variation across racial and ethnic groups in how the police were viewed, but in general, the police were given quite positive ratings. In the table below, the scores are on a 3-point scale where 1=poor, 2=average, and 3= good. The dimensions on which the police were rated were divided into two groups:
(a)    “Technical” dimensions: enforcing the law, promptly responding to calls, supplying information to the public on how to prevent crime, ensuring safety.

(b)    “Interpersonal” dimensions: being approachable and easy to talk to, treating people fairly.

Looking at the 98% of urban Ontario residents who identified themselves using one racial group, we see that all groups of urban Ontario residents, on average, rated their local police as being between ‘average’ and ‘good’.

Interpersonal Questions

Ontario – Technical questions

Ontario – Interpersonal Questions


2.57 AB (3288)

2.63 AB (3223)


2.51 C        (160)

2.50 A (150)

South Asian

2.67 ACD (261)

2.65 C (256)


2.56       (154)

2.41 BC (143)


2.41 BD (78)

2.46      (77)

Scale: 1=poor, 2=average, 3 =good (weighted N’s in parentheses).
Cells in the same grouping (province and type of question) with a superscript in common are significantly different from each other.

Without going into too much detail, there are, in addition to the generally favourable ratings, three findings that are worth keeping in mind.

  1. The racialized groups differ from one another in their views of the police on these two dimensions.
  2. The pattern of the ratings of the police across groups for the “technical questions” is not the same as for the “interpersonal” questions.
  3. In their ratings of the police on “technical” matters, Black residents are almost identical to White residents, but on the “interpersonal” dimensions Black residents rate the police lower than do Whites and South Asians.

It would appear, then, that people do differentiate between certain technical  aspects of police work and how fair/approachable the police are seen.

Citizens’ views of the police do seem to reflect how they are treated by the police. One study (B48: 8-5-5) of citizens’ views of encounters with the police in Chicago found that it was important to differentiate between citizen- and police-initiated encounters. For citizen-initiated encounters, overall satisfaction with the police was related to whether the citizen thought the police had behaved well (e.g., had been helpful, polite, thorough in their explanations, etc.) and not to the citizen’s age or race. For police-initiated contact, there was a ‘race’ effect, but it was considerably smaller in magnitude than were the effects of the quality of the encounter itself (e.g., whether the police officers explained their actions, or whether they were perceived as fair and polite).

The data would suggest, then, that the impact of race on ratings of the police is largely due to differential ratings of the quality of the police-initiated contact.

The problem for the police, however, is that negative experiences with the police have large (negative) impacts on ordinary citizens’ views of the police. Positive interactions, however, are much less important determinants of citizens’ views of the police, perhaps because ‘good behaviour’ is seen as expected (B49: 8-2-1). “For both police-initiated and citizen-initiated encounters [with the police], the impact of having a bad experience is four to fourteen times as great as that of having a positive experience. The coefficients associated with having a good experience – including being treated fairly and politely, and receiving service that was prompt and helpful – were very small and not statistically different from zero” (p. 100). It would appear that it is more important for police administrators interested in improving citizens’ assessments of the police to focus on ways of avoiding negative interactions with the public than on creating opportunities for positive interactions.

The positive aspect of these findings is that citizens’ views of the police are within the power of the police to improve. Avoiding what might be considered to be ‘offensive language’, for example, appears to be very important (B50: 7-2-3). The nature of the interaction between citizens and police officers is clearly important.

In a study of crime victims (B51:13-2-5), for example, “Respondents who felt that police did not show enough interest were much less likely to be satisfied… regardless of whether the offender [related to their victimization] had been identified and/or charged. Those who felt the police had shown enough interest, by contrast, were more likely to be satisfied… regardless of what had happened in relation to the offender” (p. 413). Outcomes did matter, but the positive impact of the outcome was considerably less in cases where police seemed uninterested in the case compared to cases where citizens thought police showed appropriate interest. Hence, police officers or police organizations that focus solely on “getting a result” (p. 417) run the risk of losing the support of the public they serve.

A policing style oriented toward procedural justice is likely to have a positive impact on public satisfaction. Aside from anything else, being effective in dealing with crime is largely out of the control of an individual police officer; but the police officer can nevertheless enhance the public’s view of police by demonstrating that a citizen’s concerns are taken seriously (B52: 11-2-3).

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Ensuring cooperation with the police

Given the research findings already summarized in this report, it should not be surprising that a study (B53: 13-5-6) of residents of London, England, found that voluntary cooperation with the police (e.g., by offering to provide them with information) appears to be related to some extent with feelings of obligation to obey the police. But in addition, high ratings of the police on lawfulness, procedural fairness and distributive fairness were also associated with the citizens’ willingness to voluntarily provide the police with crime-related information.

In a world in which terrorism appears to be a more salient problem than in the past, it is probably particularly important for the police to be able to count on members of the public to bring to their attention people or events that are potentially significant. In a study (B54: 11-4-1) of Muslim Americans’ views of cooperation with the police in New York City, it was found that broad integration into American society was important in ensuring cooperation.

Those respondents who thought that the police acted in a procedurally fair manner within their (Muslim) communities were more likely to indicate their willingness to alert the police to possible terrorism threats. In addition, those respondents who believed that anti-terrorism policies had been created in a legitimate fashion (e.g., that the community had been given an opportunity to provide input and community views were considered) were more likely to cooperate with the police in averting terrorism and they were more willing to alert the police to possible terrorism activities. Muslim Americans who reported experiencing  discrimination at school, work, or in dealing with authorities, were less willing to cooperate with the police or report possible terrorism activities to the police. Finally, those respondents who had strong identification with America (e.g., who agreed with the statement that “Being an American is important to the way I think of myself as a person”) were more willing to alert the police.

Most New York Muslim respondents indicated that they would engage in cooperative actions if asked to do so by the police, and most indicated that they would report possible terrorist related activities to the police. The variation that did exist in Muslims’ willingness to combat terrorism appears to be in large part affected by the degree to which Muslims have had positive versus discriminatory interactions with others in American society. Those who felt excluded from American society through overt discrimination, for example, as well as those who reported that the police did not treat them fairly, were less likely to be cooperative on terrorism matters.
In another study (B55:12-5-2) it was found that “The shift in policing from crime control to counterterrorism does not appear to have changed public expectations of police behaviour or to have altered the basis on which police are evaluated…” (p. 435). Procedural justice mechanisms are just as important for Muslim Americans as they are for non-Muslim minorities and for whites. “Even when police confront grave threats, both minority and majority populations expect law enforcement officers to respect procedural justice values and are more likely to withhold their cooperation if they do not…. Non-Muslims, who rate the threat of terror as larger than do Muslims, are nonetheless sensitive to procedural justice in counterterrorism policing, particularly the targeting and harassment of Muslims” (p. 436). “Three elements of procedural justice – neutrality in decision making, trust in the motives of the police, and treatment with respect – remain central to the definition of procedural justice and its effect on legitimacy” (p. 437). This is just as true in dealing with terrorism as it is in responding to ordinary crime.

A study (B56: 13-3-1) of police legitimacy in another country not immune from terrorism – Israel – arrived at very similar conclusions. In this study, a high and a low threat/risk area were compared. The performance and the efficiency of the police were important in both the ‘high terrorism’ area and in the comparison areas, but, as predicted “under conditions of threat, evaluations [of performance] play a significantly larger role in predicting police legitimacy than when there is no specific threat in the background” (p. 18). More interesting, however, is the fact that procedural justice was equally important in predicting police legitimacy in both the ‘high threat’ and the ‘low threat’ areas. “The results of the present study suggest that the desire for procedural justice is an enduring, stable trait, regardless of the security situation. Under conditions of security threats, individuals do value police performance to a greater extent when forming evaluations of police legitimacy. However, there does not seem to be a zero-sum game between performance and procedural justice: under threat, while performance increases in importance, procedural justice does not decline in importance and indeed remains the primary antecedent of legitimacy, as is the case when there is no security threat in the background” (p. 19). In more mundane terms, the police cannot afford to minimize the importance of dealing with citizens in a procedurally just fashion just because the community is facing serious external threats.

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The effects of contact with the criminal justice system

Obviously the police need to have direct contact with some youths. But there has been a fair amount of concern expressed about the possible crime-increasing effect of contact between youths and the police. In one longitudinal study (B57: 14-4-5) carried out in the US it was found that youths who were stopped and/or arrested by the police were more likely, subsequently, to reoffend than a matched comparison group. The results showed that after matching youths on their propensities to experience police contact, those who were arrested were significantly more likely to engage in delinquencies than those who were only stopped, and those stopped were more likely to engage in delinquencies than those who had no police contact. Furthermore, there was a tendency for greater amounts of police contact to reduce commitment to school, increase the likelihood the youth would have delinquent friends, and reduce their feelings of guilt about offending. Stop-and-frisk interactions between youths and police “may have the unintended consequence of increasing future delinquent involvement. Thus police practices of engaging in high rates of stops, many of which are ‘unproductive’ or ‘innocent,’ may be counterproductive” (p. 956). “For both youth who are stopped and youth who are arrested, delinquency amplification is partially explained by the attenuation of prosocial bonds, changes in deviant identity, and increased involvement with delinquent peers” (p. 956-7). Another study (B58: 15-4-8) suggests that this effect may demonstrate itself most dramatically among those who have had some, but not much, experience in offending.

Many youths commit offences, but only a subset of them are ever apprehended or arrested by the police. Thus it is possible, with surveys, to identify pairs of youths who are very similar in terms of their backgrounds, including their involvement in offending, but who differ on whether they were ever arrested. The data from one such study (B59: 14-6-1) suggest that being arrested increases subsequent violent offending; and being arrested once increases the likelihood of being rearrested. Hence it appears that being arrested makes the youth more likely to offend. But quite independent of offending rates, “a first juvenile arrest seems to increase subsequent law enforcement responses to those youth compared to other youth who offend at a comparable level but have managed to evade a first arrest. This could result from increased scrutiny of the individual’s future behaviour, by police as well as others… as well as from reduced tolerance by police … of an arrestees’ future transgressions” (p. 363). Part of the reason that being arrested may be ineffective  in reducing subsequent offending is that being arrested does not affect the perceived likelihood of being apprehended in the future (B60: 8-1-7).

These findings are not unique. One paper (B61:11-4-3) reviewed 29 separate sets of findings in which youths were, in effect, randomly assigned to receive formal court processing or less formal approaches. It found that, overall, court processing appeared to create, on average, small increases the likelihood that youths would be involved in at least some subsequent offending, though there were non-trivial differences across studies. Youths processed by the courts were, on average, involved in more crime than those processed in other ways. Similar effects were found for severity: Formal court processing of youths, if anything, increased the severity of subsequent offending.
A conservative conclusion would be that court processing does not reduce subsequent offending. “Given that the evidence indicates that there is no public safety benefit to [youth justice] system processing, and its greater costs when compared to release, even the most conservative cost-benefit analyses would favour release over [youth justice] system processing” (p. 38). Obviously some youths, because they have committed serious offences, will be brought to court in any jurisdiction. Furthermore, one cannot generalize the findings from these “matching” studies to those youth because these studies focused largely on youths charged with relatively minor offences.

At the same time it should be noted that “the data from these studies do not support a policy of establishing [formal] diversion programs for juveniles who normally would not have been officially processed….” (p. 39).

In another study (B62: 6-5-3) it was found that a youth’s likelihood of graduating from high school was lowered as a result of police or juvenile justice involvement even after controlling statistically for previous offending, parental poverty, and school ability (at age 12). A separate analysis found that “experiencing official [criminal justice] intervention in adolescence is significantly associated with reduced odds in favour of staying in school in a subsequent period” (p. 1301). An analysis of self-reported criminal activity at age 19-20 demonstrated that police or juvenile justice intervention earlier in adolescence was associated with increased criminal behaviour in early adulthood. The effect of police or juvenile justice intervention “has stronger crime amplification effects among the disadvantaged [African American youths living in poverty]” (p. 1306).

Part of the negative effects of criminal justice processing may relate to its effect on an important determinant of a person’s life chances: graduating from high school. The  evidence (B63: 14-6-2) seems quite clear that “Arrest in adolescence hinders the transition to adulthood by undermining pathways to educational attainment.” (p. 54). Youths who are arrested are more likely to drop out of school than are equivalent youths who are not arrested while in high school. Given the effects of arrest on high school completion and on enrolment in 4-year post-secondary programs, juvenile arrest can, therefore, be viewed “as a life-course trap in the educational pathways of a considerable number of adolescents in contemporary American cities” (p. 55).

A first time court appearance for a youth appears to have more negative impacts on education outcomes than a first time arrest that does not eventually lead to court (B64: 8-5- 4). These findings are similar to those reported for adults: Arrests, even when they do not lead to convictions, make it harder for someone to get a job (B65: 15-1-7).

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The police have a number of important roles to play in public safety and in the operation of the criminal justice system. The findings that we cite here which suggest that certain approaches to crime and public protection either do not work or have overall negative impacts should be placed in this larger context.

Perhaps the conclusion that one could come to that might be the least controversial would be the need to monitor and evaluate police policies related to police stops to ensure that the benefits outweigh the possible harm that could come from the intervention. This is the  same conclusion that one could apply just as easily to medical or educational interventions as to police interventions.

An important point to remember is that one cannot conclude that something is effective, just because assertions are made that it is. Data are important. And sometimes, the findings are complex. Certain kinds of activities of the police can have quite positive effects if the community is engaged in an appropriate fashion (see, for example, B66:1-6-3).

But looking at the issue that we started with – street stops by the police of people who have not apparently committed an offence – it is quite clear to us that it is easy to exaggerate the usefulness of these stops, and hard to find data that supports the usefulness of continuing to carry them out.

This is not to say that the police should not be encouraged to continue to talk to people on the street. But the evidence that it is useful to stop, question, identify, and/or search people and to record and store this information simply because the police and citizens “are there” appears to us to be substantially outweighed by convincing evidence of the harm of such practices both to the person subject to them and to the long term and overall relationship of the police to the community.

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Volume 1, Number 2, November 1997: Communities where residents can count on their neighbours to intervene when there is minor trouble, and where residents trust one another, are likely to have low levels of violence above and beyond the characteristics of the individuals who live in that neighbourhood. 

Volume 6, Number 2, December 2003: Women who live in economically disadvantaged neighbourhoods are more likely than other women to experience violence at the hands of their intimate partners. This finding appears to be  a true neighbourhood effect – that is, it holds true even when relevant characteristics of the couple are statistically held constant.

Volume 1, Number 4, April 1998: Crime may have decreased in New York during William Bratton’s reign as chief of police. But it almost certainly did not happen because he endorsed a “zero tolerance” strategy toward minor crime and other irritants. For one thing, murders decreased in other cities (e.g., San Diego where murders decreased 41%) that had completely different approaches to policing. But more importantly, the idea that crime was reduced in New York through a “zero tolerance” approach simply does not fit the facts: there were far too many other things going on in New York to make it plausible that simple changes in police strategies made a difference.

Volume 2, Number 5, September 1999: The so-called “New York Miracle” -- the large decline in homicides that took place in the early-mid 1990s was not as unusual as some have suggested. In fact, it is made up of two quite different trends: a slow and steady decline in non-gun homicides and a big decrease (after a large increase) in gun homicides. Simple explanations do not fit the data.

Volume 7, Number 5, November 2005: Ireland’s imprisonment rate increased from about 25 to 81 prisoners per hundred thousand residents between 1970 and 2002 in part as a result of a “successful” prison construction policy.

Volume 7, Number 5, November 2005: Widely publicized police interventions in three American cities show more consistency in their claims than in their effects in reducing homicide rates. 

Volume 16, Number 1, August 2016: Most of the explanations that have been offered for the ‘crime drop’ that has occurred in many western countries are plausible sounding, but they are each almost certainly inadequate.

Volume 7, Number 6, February 2006: Though not all police crackdowns on gun violence are effective, some seem to be able to suppress gun violence, at least temporarily. 

Volume 6, Number 3, March 2004: Police raids on bars in which illegal drug selling apparently was taking place had a relatively brief effect on the suppression of drug dealing in the neighbourhood. In the long term, this intervention was almost completely ineffective.

Volume 4, Number 5, March 2002: A police crackdown on drug dealers in London, England which was designed to “stifle the availability of illegal drugs on our streets” (p. 738) was described by the police as a “spectacular success” (p. 738). However, information obtained from drug users and drug dealers in this city suggests that it had no impact on drug availability or prices.

Volume 12, Number 3, January 2012: Very intensive foot patrols by police can have an impact on street crime.

Volume 13, Number 3, April 2013: Intensive foot patrols by police can reduce street crime, but the effects don’t last after police strength is reduced to normal.

Volume 15, Number 2, June 2015: Putting extra resources into the policing of high crime areas isn’t enough. To reduce violent crime police need to focus their attention on specific individuals who were known or suspected to be involved in violent crimes – an approach that can be carried out without an increase in the indiscriminate stopping and questioning of ordinary residents.

Volume 14, Number 5, November 2014: Focusing police patrols on high crime areas can reduce the incidence of some types of crimes if the police do more than merely increase the frequency of their patrols.

Volume 7, Number 6, February 2006: Police crackdowns on bad driving can prevent serious traffic accidents.

Volume 11, Number 6, April 2011: Rather than focusing on severity-based policies that increase already harsh sentences, policy makers should shift their attention to programs that use the police to make the risks and consequences of crime more clear and certain. Such a policy shift holds the promise of reducing both crime and imprisonment.

Volume 8, Number 6, July 2007: Between 1995 and 2000 the U.S. Department of Justice dropped $8.8 billion into local municipalities so that they could hire more police officers and improve community policing. These cash grants had no impact on crime.

Volume 3, Number 3, July 2000: Systematically measured neighbourhood disorder (“broken windows”) does not cause crime  in a community. “The current fascination in policy circles… on cleaning up disorder through law enforcement appears simplistic and largely misplaced, at least in terms of directly fighting crime” (p.638). “Broken windows” may be more prevalent in high crime areas, but the data suggest that disorder is not directly responsible for crime.

Volume 8, Number 5, April 2007: New York City’s attempt to snuff out violent crime by arresting those found to be smoking marijuana in public places failed.

Volume 8, Number 4, January 2007: The police strategy of targeting minor disorder on the street – so-called ‘broken windows policing’ – does not reduce crime.

Volume 9, Number 1, September 2007: A high rate of arrests for minor offences was associated with a small reduction in violent crime in New York City in the 1990s.

Volume 4, Number 5, March 2002: A policy of ‘cleaning up the streets’ and getting rid of those who make people feel uncomfortable may make good politics, but it does not appear to have much of an impact on crime.

Volume 15, Number 5, March 2016: Policing strategies that focus on local forms of disorder can be reduce crime. However, aggressive order maintenance strategies that target individual disorderly behaviours appear to be ineffective.

Volume 14, Number 5, November 2014: The police practice of “Stop, question, and frisk” appears to be an ineffective way to reduce street crime.

Volume 15, Number 6, June 2016: Police interactions with ordinary citizens involving ‘stop, question, and frisks’ appear to have very little effect on crime.

Volume 10, Number 3, April 2009: Intensive policing of minor disorder in neighbourhoods increases fear.

Volume 7, Number 1, December 2004: The perception that racial profiling by police takes place can have broad effects in the community at large: It can reduce both citizens’ assessments of the legitimacy of police actions and citizens’ general support of the police.

Volume 12, Number 5, May 2012: Canadian youths who are Aboriginal, Black, or of Arab or Middle East background are more likely than other youths be questioned by the police even when other relevant factors such as involvement in crime have been taken into account.

Volume 16, Number 3, January 2017: Black high school students in Toronto are more likely to be stopped and searched by the police than non-Black students. However, there do not appear to be differences between Black and White youths living on the street in the rate of being stopped and searched.

Volume 7, Number 2, March 2005: Do the police engage in disproportionate stops of people of certain races? The answer may depend on what is meant by ‘disproportionate.’

Volume 5, Number 4, March 2003: African-American automobile drivers are more likely to be stopped and questioned than other drivers, when taking into account the racial makeup of those who drive. In addition, African- American drivers are particularly likely to be stopped in areas which are predominantly white.

Volume 13, Number 2, February 2013: When police officers stop cars for traffic violations, the likelihood that they will also conduct a search depends not only on the race of the driver and the race of the officer, but also the racial makeup of the neighbourhood in which the stop took place.

Volume 6, Number 4, June 2004: When stopped by the police, blacks and Hispanics in the U.S. are more likely than are whites to receive a traffic ticket, be arrested, or be subject to the use of force. However, they are not more likely to be carrying contraband.

Volume 12, Number 1, August 2011: A meta-analysis of 27 independent findings demonstrates that minority suspects who come in contact with the police are more likely to be arrested than white suspects.

Volume 3, Number 1, March 2000: Black residents of both the U.S. and Canada are more likely than white residents to perceive that the criminal justice system is biased on racial grounds. In Canada, contact with the police or the courts increases the perception of bias for black residents.

Volume 14, Number 5, November 2014: Unproductive police stops of ordinary citizens leads to political alienation, distrust and, more generally, civic disengagement for people living in areas targeted by the police.

Volume 5, Number 5, May 2003: Warnings given by police to suspects concerning their rights have had a “negligible effect  on the ability of the police to elicit confessions and on the ability of prosecutors to win convictions” (p. 203).

Volume 13, Number 4, June 2013: Legally required warnings to youths about the consequences of making statements to the police do little if anything to protect youths’ rights.

Volume 11, Number 3, July 2010: Canadian police services use a wide variety of different wordings when cautioning those facing interrogation. These cautions vary considerably in their verbal complexity and the ability of listeners to understand their meanings.

Volume 15, Number 6, June 2016: It is unlikely that warnings from Canadian police given to youths are adequately understood by them.

Volume 15, Number 1, April 2015: Procedural justice is just as important for youths as it is for adults in understanding their views of the legitimacy of the police and their willingness to report crimes to the police.

Volume 15, Number 3, September 2015: People who believe that the police act unfairly are likely to believe that it is all right for ordinary people to use violence for personal protection, to resolve disputes, or to achieve political goals.

Volume 15, Number 4, December 2015: Treatment by the police that is perceived to be unfair reduces citizens’ willingness to be law abiding because being treated badly leads people to feel angry or resentful which, in turn, makes them less likely to follow the law and obey the police.

Volume 12, Number 5, May 2012: Variation across neighbourhoods in legal cynicism – i.e., lack of support for the legitimacy of laws and lack of confidence in the police – helps explain why some Chicago neighbourhoods maintained high homicide rates even when homicide rates elsewhere were decreasing.

Volume 16, Number 3, January 2017: Young Black Americans’ perceptions of criminal injustice depends on more than the nature of their own interactions with justice authorities.

Volume 7, Number 6, February 2006: Police misconduct in highly disadvantaged neighbourhoods can lead to increases in violent crime.

Volume 4, Number 4, December 2001: The justice system is judged largely on whether it is perceived as being fa ir in the manner in which it uses its authority. Drawing from a number of different surveys, it appears that procedural fairness is more important than specific outcomes.

Volume 8, Number 5, April 2007: Citizens’ level of satisfaction with the police depends primarily on how the police treat them.

Volume 8, Number 2, August 2006: Negative experiences with the police have large negative impacts on the way in which the police are rated by ordinary citizens. Positive interactions with the police, however, have little, if any, impact.

Volume 7, Number 2, March 2005: Offensive language by police officers is at least as important as their behaviour in determining the way they are seen by ordinary citizens.

Volume 13, Number 2, February 2013: Citizen satisfaction with the police is determined largely by how citizens are treated rather than by how successful the police are in locating or charging an offender.

Volume 11, Number 2, May 2010: The police have direct control over how favourably they are seen by crime victims. Although victims generally think less favourably about the police than non-victims, the police can mitigate this effect by taking victims’ concerns seriously.

Volume 13, Number 5, August 2013: People judge the legitimacy of the police by whether the police follow the law, whether the police have been procedurally fair in their dealings with citizens, the fairness of the outcome of encounters with the police, and the effectiveness of the police. The perceived fairness of the police predicts voluntary cooperation with them.

Volume 11, Number 4, September 2010: The willingness of members of the Muslim community in New York to work voluntarily with the police in combating terrorism is determined, in part, by how Muslims are treated by the police and others in the community.

Volume 12, Number 5, May 2012: Treating suspects fairly is important even in the war against terrorism.

Volume 13, Number 3, April 2013: Even in situations in which citizens face terrorist threats and attacks, the legitimacy of the local police is determined, in large part, by whether the police are perceived to be treating people in a procedurally just fashion.

Volume 14, Number 4, August 2014: Being stopped by the police increases future offending.

Volume 15, Number 4, December 2015: Contact with the police can increase the likelihood of future violent offending for those already involved in small amounts of violent crime, but not for those who, previously, were not involved in violent crime.

Volume 14, Number 6, January 2015: Being arrested by the police increases the likelihood that a youth will commit further offences and, quite independently, also increases the likelihood that the youth will be arrested again.

Volume 8, Number 1, July 2006: Being arrested does not increase youths’ perceptions that they will be caught in the future.

Volume 11, Number 4, September 2010: Formal processing of youths in the youth justice system does not reduce subsequent offending. If anything, youths processed formally are more likely to re-offend than those screened out of the formal system or processed informally.

Volume 6, Number 5, August 2004: Contact with the formal juvenile justice system increases the level of criminal activity in early adulthood.

Volume 14, Number 6, January 2015: Arresting young people when they commit offences reduces the likelihood that they will graduate from high school.

Volume 8, Number 5, April 2007: Being arrested and taken to court reduces a youth’s chances of finishing high school.

Volume 15, Number 1, April 2015: Records of arrests by police not leading to convictions make it difficult to get a job.

Volume 1, Number 6, September 1998: Crime can be reduced by the collective action of those who live or work in local city blocks that have drug and disorder problems. The police can help by supporting groups on the  block and by coordinating services that address non-crime problems on the block.

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