Field Notes

concept

Displacement

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Displacement is the relocation of a controlled behaviour from one place, time, target, offence, or tactic to another as a result of a prevention measure.1 The concept comes from situational crime prevention, where it is the standard objection to any measure that blocks an opportunity without addressing motivation, and it generalises to any intervention whose effect is measured at the point it controls.

The concept’s practical weight is that it separates two things an evaluation at the controlled point cannot tell apart: a measure that reduced the behaviour, and a measure that moved it somewhere the evaluation is not looking.

The forms it takes

Analyzing Crime Displacement and Diffusion gives five forms, and the distinction matters because a measure can block one and invite another:

Form The offender changes
Temporal when the behaviour happens
Spatial where, switching from targets in one location to another
Target which kind of target is chosen
Tactical the method used to carry it out
Offence the form of the behaviour itself

A sixth, perpetrator displacement, is sometimes added for the case where one actor is removed and another takes their place.

Displacement also has a direction. Barr and Pease distinguish benign displacement, where the behaviour moves to a less harmful target, place, or form, from malign displacement, where it concentrates on more vulnerable victims or shifts to more serious offences.2 An evaluation that counts displaced events without weighting harm can report a wash where the intervention in fact helped or hurt.

The complement is diffusion of benefits: a reduction that extends beyond the targeted area, period, or offence although the measure was never applied there.3 It is the same causal logic running the other way, and an evaluation that looks for displacement without looking for diffusion is measuring only the side that makes the intervention look worse.

Displacement is the exception, not the rule

The empirical record does not support treating displacement as automatic. Guerette and Bowers reviewed 102 situational crime-prevention evaluations yielding 574 observations of possible displacement or diffusion. Displacement appeared in 26 percent of them and diffusion of benefits in 27 percent.4 Earlier reviews point the same way: Eck found 91 percent of 33 studies reporting no or little displacement, and Hesseling found 40 percent of 55 studies reporting none at all.5 Where displacement does occur, it “tends to be less than the gains achieved by the response.”6

The theoretical reason is that the inevitability claim assumes a fixed quantity of motivation that must find an outlet. That assumption “fails to recognize the important role that opportunity and temptation play,” and the observed behaviour is conditional: actors relocate “only when the risks and effort of committing new crimes are worth the reward.”7 Displacement is therefore likeliest where an equally easy and equally rewarding alternative sits nearby, and that is an empirical question about the specific alternatives, not a general property of restrictions.

Measuring it requires choosing where to look

Displacement is detectable only in a catchment area the evaluation decided in advance to observe, and that choice drives the answer. Guerette’s criteria are logical relation or proximity to the intervention, proportionate size, and freedom from contamination by other interventions.9 Too small an area and the relocation falls outside it; too large and the displaced volume dissolves into background variation. Using several catchment areas of different sizes is the practical hedge.

The measurement problem is why displacement is easier to argue than to show, and why an argument that names displacement as a cost owes a statement of where the behaviour is supposed to have gone.

Beyond crime

The vault uses the concept mostly outside policing, for restrictions on lawful conduct online, where the displaced actor is an ordinary user rather than an offender. The mechanism transfers because it depends only on a controlled point, an uncontrolled alternative, and an actor comparing effort against reward. The empirical base rates do not transfer automatically: they were measured on situational crime prevention, and a substitute that is one tap away is not the same choice architecture as a substitute across town. Does online displacement behave like crime displacement tracks what would settle that.

Children’s circumvention behaviours online is the closest measured case. Among UK 11- to 17-year-olds, 53 percent had avoided age checks by choosing platforms that did not impose them — migrating to sites with no check or an easily tricked one — against 10 percent using location-changing tools. That is offence and target displacement dominating tactical displacement, and it is measured rather than assumed, which is what makes it usable. Alternatives to age verification, Less harmful social media, and Age-verification circumvention services each turn on where a restricted user goes next.

  1. Analyzing Crime Displacement and Diffusion, “Defining Displacement”: “Crime displacement is the relocation of crime from one place, time, target, offense, or tactic to another as a result of some crime prevention initiative.” ↩

  2. The distinction is Barr and Pease’s (1990), reported in Analyzing Crime Displacement and Diffusion. ↩

  3. Analyzing Crime Displacement and Diffusion, crediting Clarke and Weisburd (1994). ↩

  4. Rob T. Guerette and Kate J. Bowers, “Assessing the extent of crime displacement and diffusion of benefits”, Criminology 47(4) (2009): 1331–1368, summarised in Analyzing Crime Displacement and Diffusion. ↩

  5. Analyzing Crime Displacement and Diffusion, reporting Eck (1993) and Hesseling (1994). ↩

  6. Analyzing Crime Displacement and Diffusion, “The Evidence on Displacement”. ↩

  7. Analyzing Crime Displacement and Diffusion, “Why Displacement May Not Occur”. ↩

  8. Analyzing Crime Displacement and Diffusion, “Introduction” and “The Evidence on Displacement”. ↩

  9. Analyzing Crime Displacement and Diffusion, Table 3, “Criteria for Selecting Displacement/Diffusion Areas”. ↩

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