The Specific Deterrent Effect of ShortTerm License Suspension

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The Specific Deterrent Effect of Short-Term
License Suspension
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Published March 2007 In Partnership with The
Traffic Injury Research Foundation Report availab
le online at www.aaafoundation.org
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Introduction

• Short-term suspensions have been used in some
  Canadian provinces for more than 20 years
• There has never been a comprehensive evaluation
  of short-term license suspensions
• Evaluation of short-term license suspension law
  in Saskatchewan
• Funding provided by AAA Foundation for Traffic
  Safety

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Short-term License Suspension in Canada

• Administrative sanction applied by police to
  drivers with low BACs (below the legal limit for
  DWI conviction)
• License is suspended at the scene for 12-24 hours
• No involvement of the courts
• Viewed as an immediate, swift, relatively
  efficient means of removing drinking drivers from
  the road

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Short-Term Suspensions in Saskatchewan

• Introduced in Saskatchewan in August 1996
• Applied to drivers with BAC of .04 and below
  .08
• First STS results in 24-hour licence suspension
• Subsequent STS results in remedial programs and
  longer suspensions

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Outcomes of STS

• General deterrence
• To deter drivers from engaging in prohibited
  behaviour by threat of punishment
• Specific deterrence
• Application of punishment to further deter those
  drivers who do engage in the behaviour get
  caught

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Specific Deterrent Effect

• If effective, less likely for drivers to repeat
  behavior that led to the Short-Term License
  Suspension
• Use re-offence rates
• Three comparison groups
• STS
• issued Short-Term Suspension during first two
  years of law
• Criminal Code DWI (CC)
• arrested for DWI during first two years of law
• Clean
• no alcohol-related offences during first two
  years of law

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Timeline for Analysis
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Group Membership Summary
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Analysis of Re-offences

• Survival analysis
• offence-free over follow-up period
• Survival time
• Number of days from index offence to first
  subsequent STS or CC
• Once a driver has re-offended, they are dropped
  from the analysis

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STS Re-offences (No Priors)

• Drivers without DWI conviction prior to
  introduction of STS law

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CC Re-offences (No Priors)

• Drivers without DWI conviction prior to
  introduction of STS law

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Total Offence Tallies (No Priors)

• STS Group
• Higher proportion with multiple STS offences
• CC Group
• Higher proportion with multiple CC offences

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Results For Drivers With Prior Criminal Code DWI
Convictions

• STS Group
• 100 (n164) of STS group re-offended
• Majority (88) re-offended with a CC
• Higher proportion of multiple offences (CC STS)

• Drivers with DWI convictions prior to
  introduction of STS law

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Conclusions

• STS Group (No Priors)
• Support for Specific Deterrence
• Majority (75) did not re-offend
• Those who did re-offend were more likely to do so
  with another STS rather than a Criminal Code DWI
• Small subset (8) did re-offend with more
  serious drinking driving behaviour Criminal
  Code DWI

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Conclusions cont

• STS Group (With Priors)
• Lack of specific deterrent effect is evident
• Police discretion could have led to group
  contamination
• Priors need to be considered when discretion is
  used