Crime Displacement and Diffusion of Benefits

Crime displacement and diffusion of benefits are the two competing empirical possibilities that any place-based crime prevention intervention might produce beyond its immediate target location, with displacement referring to the relocation of criminal activity to nearby untreated areas and diffusion of benefits referring to the unanticipated spread of crime-reduction effects to those same untreated surrounding areas. Within the Environmental Criminology silo, this article examines the theoretical basis for displacement concerns, the several distinct forms displacement can theoretically take, the accumulated empirical research testing for both displacement and diffusion effects, and the practical implications this research carries for evaluating the many place-based interventions examined throughout this silo’s companion articles.

Introduction

Displacement theory has functioned as environmental criminology’s most persistent internal critique since the field’s earliest formulations, since a purely offender-centered account of criminal motivation would predict that any successful place-based intervention should simply relocate rather than genuinely reduce crime, as motivated offenders, denied opportunity at one location, seek out comparable opportunity elsewhere. This displacement concern carries direct implications for how researchers and policymakers should interpret the substantial body of place-based crime prevention research examined throughout this Environmental Criminology silo, since apparent local crime reductions documented at treated hot spots, examined in the companion article on Hot Spots Policing elsewhere in this silo, would carry considerably less practical significance if they merely reflected geographic relocation rather than genuine reduction in total criminal activity.

This article proceeds by examining displacement theory’s underlying logic and its several distinct theoretical forms, the diffusion of benefits phenomenon that has emerged as displacement’s empirically documented counterpart, the systematic evidence Rob Guerette and Kate Bowers’s landmark research review has assembled testing both possibilities, and the practical implications this evidence carries for evaluating and designing place-based prevention interventions. David Weisburd’s broader assessment of the place-based crime prevention research tradition situates displacement theory’s persistent critique as a productive rather than merely obstructive force within environmental criminology’s development, arguing that the discipline’s willingness to rigorously test rather than simply dismiss the displacement objection has substantially strengthened the overall credibility of the place-based prevention paradigm examined throughout this encyclopedia’s treatment of environmental criminology (Weisburd, 2015).

The Theoretical Logic of Displacement

Five Forms of Displacement

Criminologists have identified several theoretically distinct forms displacement might take, extending well beyond the simple geographic relocation most casual discussion of the concept assumes, including temporal displacement, in which offenders shift the timing of their offending to periods when a given intervention is not in effect, tactical displacement, in which offenders adopt different methods to circumvent a specific prevention measure, target displacement, in which offenders select different victims or targets within the same general location, offense displacement, in which offenders switch to different offense types altogether, and the more familiar spatial displacement, in which offenders relocate their activity to nearby untreated geographic areas (Guerette & Bowers, 2009). This five-form typology, developed through the accumulated situational crime prevention literature, has proven essential for comprehensive displacement evaluation, since research measuring spatial displacement alone while ignoring the other four forms risks substantially understating the true extent of any displacement that has actually occurred. Marcus Felson’s broader treatment of crime and everyday life offered a complementary perspective on this typology, noting that offense and target displacement in particular require offenders to possess and apply genuinely transferable criminal skills across different offense categories or victim types, a skill-transfer requirement that plausibly limits how readily displacement of these particular forms actually occurs relative to the more straightforward spatial and temporal displacement forms that require no new skill acquisition whatsoever (Felson, 1998).

Ronald Clarke’s situational crime prevention framework, examined in the companion article on CPTED in America elsewhere in this silo, directly anticipated this displacement concern in its original formulation, since Clarke’s rational choice foundations imply that a sufficiently motivated offender facing blocked opportunity at one location, through one method, or against one target, should rationally seek out the next most attractive available alternative rather than simply abandoning criminal intent altogether (Clarke, 1997).

Theoretical Predictions of Complete Versus Partial Displacement

Early displacement skeptics effectively argued for what researchers term the hydraulic or complete displacement hypothesis, the assumption that criminal motivation functions as a fixed, constant quantity that must express itself somewhere, such that blocking one opportunity mechanically produces an equal and opposite increase in offending through some alternative form, location, or target (Guerette & Bowers, 2009). This complete displacement hypothesis, while intuitively appealing to critics skeptical of situational crime prevention’s practical value, rests on an assumption about fixed, unlimited offender motivation that routine activity theory and rational choice perspectives, examined in the companion article on Place and Crime elsewhere in this silo, directly contradict, since both theoretical traditions hold that criminal behavior depends substantially on situational opportunity rather than on a fixed underlying motivational reservoir requiring expression regardless of circumstance. Francis Cullen’s broader assessment of theoretical developments within criminology credited this direct theoretical challenge to the hydraulic displacement assumption with helping establish opportunity-based explanation as a genuinely credible alternative to the more deterministic offender-centered theories that had dominated much of earlier twentieth-century criminology, a credibility subsequently reinforced by the empirical displacement research this article examines (Cullen, 2011).

Derek Cornish and Ronald Clarke’s rational choice perspective supplies the theoretical basis for expecting displacement to be partial rather than complete even where it does occur, since their effort-risk-reward framework implies that offenders will only pursue displaced alternative opportunities that remain sufficiently attractive relative to the increased effort or risk the original blocked opportunity’s absence now requires, meaning that some proportion of blocked criminal motivation should simply go unexpressed rather than mechanically displacing to an alternative (Cornish & Clarke, 1986).

Diffusion of Benefits

Defining and Documenting the Diffusion Phenomenon

Diffusion of benefits, sometimes termed the halo effect, refers to the empirically documented phenomenon in which place-based crime prevention interventions produce crime reduction extending beyond their immediate target area into adjacent, untreated locations, an effect operating in the opposite direction from displacement and reflecting offenders’ apparent tendency to overestimate the geographic scope of a given intervention’s actual reach (Clarke & Weisburd, 1994). Ronald Clarke and David Weisburd’s foundational theoretical treatment of this phenomenon proposed that offenders, uncertain of an intervention’s precise geographic boundaries, may avoid a broader surrounding area than the intervention actually covers, generating crime reduction in nearby untreated locations through this uncertainty-driven caution rather than through any direct mechanical effect of the intervention itself. Anthony Braga’s original hot spots policing meta-analysis, examined in fuller depth in the companion article on Hot Spots Policing elsewhere in this silo, independently documented diffusion-consistent findings across several of the studies included in his synthesis, providing early corroborating evidence for the Clarke-Weisburd diffusion concept from a research tradition developed largely independently of the situational crime prevention literature from which the concept itself originated (Braga, 2001).

This diffusion mechanism carries an important asymmetry with displacement, since diffusion depends on offenders’ imperfect information regarding an intervention’s precise boundaries, while displacement, at least in its more deliberate tactical and target forms, presumes offenders possess relatively complete and accurate information regarding where opportunity has been blocked and where comparable alternative opportunity remains available, an asymmetry that may help explain why the accumulated empirical evidence, examined below, has generally found diffusion effects more prevalent than displacement effects across the situational crime prevention literature.

Mechanisms Underlying Diffusion

Beyond offender uncertainty regarding intervention boundaries, diffusion of benefits may also reflect broader deterrent signaling effects, in which a documented intervention at one location communicates a jurisdiction’s or property owner’s general increased vigilance extending beyond the specific treated location, discouraging offending at nearby locations independent of any direct boundary-uncertainty mechanism (Guerette & Bowers, 2009). Daniel Nagin’s broader deterrence research supplies a relevant theoretical foundation for this signaling-based diffusion mechanism, since his finding that perceived certainty of apprehension exerts a stronger deterrent effect than actual objective apprehension risk implies that offenders’ subjective, and potentially inaccurate, perception of an intervention’s geographic reach may matter more for diffusion than the intervention’s precisely documented actual boundaries (Nagin, 2013). This signaling-based diffusion mechanism connects directly to the broader deterrence theory examined throughout this encyclopedia’s treatment of criminological theory, since general deterrent signaling operates through offenders’ updated perception of overall apprehension risk within a broader area rather than through the more narrowly targeted specific deterrence a location-specific intervention directly produces.

This dual-mechanism understanding of diffusion, encompassing both boundary uncertainty and broader deterrent signaling, has informed contemporary place-based intervention design, with some practitioners deliberately maintaining ambiguity regarding an intervention’s precise geographic boundaries in an effort to maximize the diffusion of benefits extending beyond the immediately treated location.

Variation Across Crime Types and Intervention Settings

Property Crime Versus Violent Crime Displacement Patterns

Guerette and Bowers’s systematic review found that displacement and diffusion patterns varied meaningfully across offense categories, with property crime interventions, including burglary and vehicle theft prevention, showing somewhat more mixed displacement and diffusion results than violent crime interventions, a pattern the researchers attributed partly to property offenders’ generally greater target flexibility relative to violent offenders, whose behavior more often responds to situational and relational triggers less readily displaced to alternative locations or targets (Guerette & Bowers, 2009). This crime-type variation carries direct implications for the setting-specific applications examined throughout this silo’s companion articles, since interventions targeting predominantly property crime, including many of the environmental design strategies examined in the companion article on Crime and the Physical Environment elsewhere in this silo, may warrant somewhat more careful displacement monitoring than interventions targeting predominantly violent offense categories.

Anthony Braga and colleagues’ gun violence-specific research, examined in the companion article on Crime Concentration elsewhere in this silo, found particularly limited displacement for firearm violence specifically, a pattern consistent with the broader theoretical expectation that serious violence, often embedded within specific relational and territorial dynamics examined in the companion article on Environmental Criminology and Gang Territory elsewhere in this silo, displaces less readily than more purely opportunistic property offending (Braga, Papachristos, & Hureau, 2010). Lawrence Sherman’s earlier foundational hot spots research anticipated this offense-type distinction, noting even in the original Minneapolis concentration study that different offense categories displayed somewhat different concentration and stability patterns, a heterogeneity that subsequent displacement research examined in this section has confirmed carries direct implications for how uniformly displacement findings from one offense category should be generalized to others (Sherman, Gartin, & Buerger, 1989).

Drug Market Displacement and Market Dynamics

Drug markets have received particularly sustained displacement research attention given their status as paradigmatic crime attractors, examined in the companion article on Crime Generators and Crime Attractors elsewhere in this silo, since drug markets’ fundamentally economic character, requiring buyers and sellers to successfully locate one another, might plausibly generate stronger displacement pressure than opportunistic property or violent offending lacking this transactional coordination requirement (Weisburd & Green, 1995). Weisburd and Green’s Jersey City research addressed this specific concern directly, finding that despite drug markets’ transactional character, police intervention at identified drug-market hot spots produced diffusion rather than displacement, a finding the researchers attributed to the considerable coordination costs drug transactions require, including establishing trust and communication channels between buyers and sellers that cannot be instantaneously reestablished at a new location following disruption of an established market.

This drug-market finding has proven particularly influential for policy debates regarding drug enforcement strategy specifically, examined in the companion article on Environmental Criminology and Drug Markets elsewhere in this silo, since it directly countered a commonly voiced practitioner concern that drug-market enforcement inevitably simply relocates rather than reduces drug distribution activity within a given jurisdiction.

Critiques and Refinements of Displacement Theory

Benefits of Displacement When It Does Occur

Some criminologists have argued that even where genuine displacement occurs, it may not represent an unambiguously negative outcome, since displacement to a less serious offense type, a less vulnerable target population, or a location with stronger existing guardianship capacity could plausibly represent a net social benefit even without any reduction in raw total offense count (Guerette & Bowers, 2009). This benign-displacement argument has generated some controversy within the broader situational crime prevention literature, since critics have countered that treating any form of displacement as acceptable risks understating genuine victim harm, particularly where displacement shifts offending toward less-resourced communities with weaker capacity to absorb or respond to the relocated criminal activity. Michael Tonry’s broader critique of American crime policy raised a parallel equity concern regarding place-based prevention more generally, cautioning that any crime-control strategy, including hot spots policing and related place-based approaches, requires ongoing attention to whether its benefits and burdens distribute equitably across a jurisdiction’s varied communities rather than assuming that aggregate crime-reduction statistics alone establish a strategy’s overall social value (Tonry, 2011).

Ronald Clarke’s own assessment of this benign-displacement debate has generally sided with cautious acceptance of the argument in specific, carefully documented circumstances, while emphasizing that practitioners should never assume benign displacement without direct empirical verification, since the theoretical possibility of beneficial displacement does not establish that any particular real-world displacement instance actually achieves a net positive redistribution of harm (Clarke, 1997).

Continued Measurement Challenges

Despite Guerette and Bowers’s comprehensive synthesis, displacement and diffusion measurement continues to face persistent methodological challenges, including determining the appropriate geographic radius within which to search for displacement or diffusion effects, a boundary-setting decision that can substantially influence study conclusions since a radius set too narrowly may miss genuine displacement occurring just beyond the measured boundary while a radius set too broadly may dilute genuine local effects with unrelated background variation (Ratcliffe, 2004). Jerry Ratcliffe’s methodological research on spatial crime analysis specifically addressed this boundary-setting challenge, proposing more principled, empirically grounded approaches to selecting displacement search radii based on the specific offense type and intervention mechanism under evaluation rather than relying on arbitrary standardized distance thresholds.

This continued methodological refinement illustrates that displacement and diffusion research, despite Guerette and Bowers’s substantial synthesis achievement, remains an active rather than fully settled area of environmental criminology, with ongoing methodological development continuing to sharpen researchers’ capacity to detect and accurately characterize these effects across the expanding range of place-based interventions examined throughout this encyclopedia’s treatment of environmental criminology.

Systematic Empirical Evidence

Guerette and Bowers’s Comprehensive Review

Rob Guerette and Kate Bowers’s 2009 systematic review remains the most comprehensive empirical assessment of displacement and diffusion across the accumulated situational crime prevention literature, synthesizing 102 separate evaluations of place-based interventions and finding that diffusion of benefits was reported more frequently than displacement across the studies examined, with diffusion documented in approximately forty percent of studies measuring for it while displacement was documented in a considerably smaller proportion of studies measuring for it (Guerette & Bowers, 2009). This finding directly challenged the assumption, common among earlier displacement skeptics, that displacement should be expected as a near-automatic consequence of successful place-based intervention, instead suggesting that genuine crime reduction, and even beneficial spillover, represents the more empirically typical outcome.

Guerette and Bowers’s review also found that the specific type of situational crime prevention technique employed shaped the relative likelihood of displacement versus diffusion, with interventions targeting a broader range of the effort-risk-reward mechanisms Clarke’s situational crime prevention framework specifies generally showing less displacement than interventions relying on a single narrow mechanism, such as target hardening alone, suggesting that more comprehensive interventions may leave offenders with fewer viable displacement alternatives than narrower, single-mechanism interventions.

Applications to Hot Spots Policing Specifically

David Weisburd and Lorraine Green’s earlier drug-market-specific research, examining Jersey City police crackdowns on identified drug-market hot spots, found measurable diffusion of benefits to nearby blocks rather than the displacement critics had predicted, an influential early contribution to the hot spots-specific displacement literature examined in fuller depth in the companion article on Hot Spots Policing elsewhere in this silo (Weisburd & Green, 1995). This drug-market finding proved particularly significant given that drug markets represent a paradigmatic crime attractor, examined in the companion article on Crime Generators and Crime Attractors elsewhere in this silo, and critics had specifically predicted that attractor-type crime, driven by deliberate offender targeting rather than incidental opportunity, should display particularly strong displacement given offenders’ presumed detailed knowledge of alternative market locations.

Anthony Braga’s broader meta-analytic synthesis of hot spots policing evaluations similarly found that studies measuring for displacement effects around treated hot spots generally failed to document meaningful displacement, reinforcing Guerette and Bowers’s broader conclusion within the specific hot spots policing context this article’s companion article examines in fuller operational detail (Braga, Papachristos, & Hureau, 2014).

Practical and Methodological Implications

Evaluation Design Requirements

The accumulated displacement and diffusion research carries direct methodological implications for how researchers should design place-based intervention evaluations, since rigorous evaluation requires measuring outcomes not merely at the treated location itself but across a sufficiently broad surrounding geographic area to detect both potential displacement and potential diffusion, a methodological requirement that considerably complicates evaluation design relative to studies measuring outcomes solely at the treatment location (Guerette & Bowers, 2009). John Eck and David Weisburd’s broader place-based theoretical framework noted that this expanded measurement requirement connects directly to the place-management concept examined in the companion article on Place and Crime elsewhere in this silo, since a treated location’s specific place-management characteristics likely shape not only its own crime-reduction response but the extent to which nearby locations, sharing similar place-management conditions or lacking them, experience displacement or diffusion effects (Eck & Weisburd, 1995). This broader-area measurement requirement has become a standard methodological expectation for rigorous contemporary place-based crime prevention evaluation, with the strongest available evidence, including the hot spots policing meta-analyses examined in the companion article on Hot Spots Policing elsewhere in this silo, consistently incorporating this broader geographic measurement approach.

This methodological standard has also shaped how crime-analysis practitioners approach the geographic information systems examined in the companion article on GIS and Crime Mapping elsewhere in this silo, since detecting displacement or diffusion effects requires spatial analytical tools capable of tracking crime patterns across a sufficiently extended geographic buffer surrounding any treated location rather than analytical tools focused narrowly on the treatment location alone. Ross Matsueda’s broader theoretical assessment of place-based criminology noted that this expanded measurement requirement reflects a more general methodological principle applicable well beyond displacement research specifically, namely that place-based criminological claims of any kind require attention to the appropriate spatial scale of analysis, a principle equally relevant to the modifiable areal unit concerns examined in the companion article on Place and Crime elsewhere in this silo (Matsueda, 1988).

Implications for Policy and Program Design

The overall pattern of accumulated evidence, favoring diffusion of benefits over displacement across the substantial majority of rigorously evaluated place-based interventions, has supplied policymakers and practitioners with considerable reassurance regarding place-based crime prevention’s genuine value, addressing what had historically been one of the most persistent skeptical objections to the entire place-based prevention paradigm examined throughout this encyclopedia’s treatment of environmental criminology (Guerette & Bowers, 2009). This evidentiary reassurance has directly supported the continued expansion of hot spots policing and related place-based strategies, since policymakers and practitioners can now cite a substantial, methodologically rigorous evidence base indicating that such strategies typically produce genuine rather than merely relocated crime reduction. Cynthia Lum and Christopher Koper’s broader evidence-based policing synthesis incorporated this displacement and diffusion evidence directly into their overall assessment of place-based policing effectiveness, concluding that the combination of demonstrated crime-reduction effects and generally favorable displacement and diffusion patterns together supplied among the strongest evidentiary cases available for any contemporary American policing strategy (Lum & Koper, 2017).

This favorable evidentiary pattern does not eliminate displacement entirely as a legitimate ongoing concern, since Guerette and Bowers’s review documented meaningful displacement in a nontrivial minority of the studies examined, and continued evaluation attention to displacement possibilities remains warranted for any newly designed or newly implemented place-based intervention rather than assuming the generally favorable aggregate pattern automatically applies to every specific intervention design.

Conclusion

Crime displacement and diffusion of benefits together represent the two theoretically possible, empirically distinguishable consequences that place-based crime prevention interventions might produce beyond their immediate target location, with the accumulated evidence, most comprehensively synthesized in Guerette and Bowers’s landmark systematic review, finding diffusion of benefits considerably more prevalent than displacement across the substantial body of rigorously evaluated situational crime prevention research this article has examined. Vold, Bernard, and Snipes’s comprehensive survey of theoretical criminology situates this displacement and diffusion research among environmental criminology’s most methodologically rigorous contemporary contributions, noting its unusual willingness to test rather than assume away a legitimate theoretical objection to the field’s central practical recommendations (Vold, Bernard, & Snipes, 2002). This favorable evidentiary pattern, further confirmed within the specific hot spots policing context examined in the companion article on Hot Spots Policing elsewhere in this silo, has substantially strengthened the practical and theoretical case for the place-based prevention strategies examined throughout this encyclopedia’s broader treatment of environmental criminology.

This displacement and diffusion research illustrates environmental criminology’s capacity for genuine self-correction, directly testing rather than merely dismissing a serious theoretical objection to its own practical recommendations, a methodological rigor that has substantially strengthened rather than undermined confidence in the place-based crime prevention paradigm this silo’s companion articles examine throughout. David Weisburd and Lawrence Sherman’s original 1995 Minneapolis Hot Spots Patrol Experiment, examined in fuller depth in the companion article on Hot Spots Policing elsewhere in this silo, included some of the earliest systematic displacement monitoring within a randomized hot spots evaluation design, establishing a methodological precedent for the broader displacement-monitoring standard subsequent hot spots research, including Guerette and Bowers’s comprehensive synthesis, has since followed (Weisburd & Sherman, 1995).

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