Reading summary

Situational crime prevention Displacement & Diffusion

1

Review of SCP • 5 technique categories

– Increase effort – Increase risk – Reduce rewards – Reduce provocations – Remove excuses

• Opportunity is key theoretical assumption of SCP – Opportunity plays a role in causing all crime

• Crime opportunities (CO) are highly specific • COs are concentrated in time/place • COs depend on everyday movements, routines • Some products offer more tempting COs • Social changes (e.g., technology) produce new COs • COs can be reduced

– Reducing opportunities does not usually displace crime – Focused opportunity reduction can produce wider declines in crime

Displacement of crime? • Claim: SCP does not truly prevent crime b/c motivated

offenders will just change targets – Crime can be displaced by SCP efforts

• “change in crime due to preventative actions” – Displacement shares main assumptions of opportunity theories

• Offenders respond to opportunities to commit crime (risks, reward, effort, provocation, etc.)

• SCP is flawed b/c opportunity is not the only cause of crime – Crime occurs due to root causes in the individual’s development and

environment that create motivation to offend • SCP shifts where motivated offenders find those opportunities

– This isn’t really prevention

Four assumptions of displacement • (1) Offenders make rational choices – Offenders respond to payoff, effort, risks • If offenders did not, SCP would not reduce crime or

cause displacement

• (2) Crime is inelastic – “not responsive to changes in price” • Offenders will not change their behavior just because

crime becomes more “costly” – So increasing risks, reducing rewards, and increasing effort will

not change offender behavior because the motivation to commit crime is independent of situational opportunity

Four assumptions of displacement

• (3) Offenders have mobility – Ability to change time, place, tactic, target, etc. • If offenders do not have this ability, displacement will

not occur – Some offenders may have less mobility than others (e.g., youth) – Also may be natural barriers (highway, river, etc.) that limit

movement among targets

• (4) Alternative targets/choices are available – As long as other criminal opportunities exist, motivated

offenders will find them

Forms of displacement • Territorial displacement

– Change in place

• Temporal displacement • Change in time

• Tactical displacement – Change in methods

• Target displacement – Change in victim

• Functional displacement – Change in crime type

• Perpetrator displacement – Change in offender

Territorial

• Change in crime from one geographical area to a contiguous geographical area – E.g., Neighborhood

watch program causes burglaries to reduce by 50% in neighborhood, but burglaries increase by 30% in contiguous neighborhood

Temporal

• Change in crime from one time to a different time – E.g., Temporal SCP

measures such as a night citizen patrol causes more crime to move to daytime

– E.g., SCP measures aimed at weekend activities shifts crime to weekdays

Tactical • Change in methods

used to commit crime – E.g., Installation of better

door locks causes burglars to force entry through window

– E.g., Tighter gun control measures cause armed robbers to use knives or some other weapon

Target • Change in victim of

crime within same area – E.g., Home alarms cause

burglars to shift from houses w/ alarms to houses w/out alarms

– E.g., Immobilization software in new cars causes car thieves to switch to older cars

Functional

• Offender shifts from committing one type of crime to another – E.g., Making burglary

more difficult through increased home alarms causes offenders to commit more robberies or larcenies in public spaces

Perpetrator

• One offender stops, another offender replaces the first – E.g., Offender stops

dealing drugs in response to increased street lighting, which causes another motivated offender to begin dealing drugs in the same area (given new opportunity)

Malign vs. benign displacement • Malign displacement

– Changes in crime cause more undesirable outcomes • E.g., SCP measures cause decrease in local burglaries (non-violent offense)

– Displacement causes increase in local robberies (violent offense)

• Benign displacement – Changes in crime benefit society

• E.g., SCP measures cause crime to shift from violent theft (e.g., robbery) to non-violent theft (e.g., identity theft)

• Displacement may create “crime fuses” – Areas where crime moves and is allowed to operate without

bothering rest of society • Like a fuse, this can “explode” into an uncontainable situation

Diffusion of benefits • Crime prevention efforts may spread benefits beyond

the targeted people/places/times – Also called “halo effect” or “free bonus effect”

• Can be considered the other side of the coin to displacement

• What would cause diffusion of benefits? – Deterrence

• SCP measures deter offending beyond targeted offense by increasing the perception of risk – E.g., CCTV in one car park cause auto theft to decrease in all car parks in an area

– Discouragement • SCP measures aimed at one crime discourage other crimes by

increasing effort to commit any crimes in an area – E.g., Improving street lighting in an area discourages potential offenders from

looking for other “unlit” areas due to increased effort

Evidence of displacement? • Evaluations often do not measure displacement

– Two studies found little evidence of displacement • Guerette & Bowers (2009) found displacement in 29% of SCP

evaluations in systematic review (n = 102) – Temporal was most common; tactical was least common – Where it occurred, displacement was typically smaller than crime reduction

» I.e., benign displacement • Telep et al. (2014) found that spatial displacement in area-based SCP

interventions was not common – Across 127 coded effect sizes from 43 studies, found displacement of crime in

11.9% of effects » Crime reduced in 46% of outcomes

– A cro ss

• Little reason to expect total displacement of crime – Even if some displacement occurs, net result would be crime

reduction • So displacement is not an inevitable result of SCP, but is possible

and should be considered in evaluations of SCP measures

Evidence of diffusion? • Can be measured by looking at crime reductions

in areas surrounding the target area – But reduction in crime in target and control areas could

indicate unrelated crime reduction in society at large • Another issue is that diffusion effects and displacement effects

could offset, making it hard to detect either

• Diffusion is hard to measure! – Some evaluations have uncovered evidence of diffusion,

similar (but opposite) to evidence of displacement • Guerette & Bowers (2009) found diffusion of benefits in 27% of

SCP evaluations (n = 102) • Telep et al. (2014) found diffusion of benefits in 22.2% of

observed effects