The effectiveness of alcohol interlocks in reducing repeat drink driving and improving road safety

Recidivist drink driving Drink-driving Driver education Alcohol-related crime Driving offences Road safety New South Wales

The Mandatory Alcohol Interlock Program (MAIP) was introduced in February 2015 and applies to offenders convicted of refusing a breath test, high range drink driving and repeat drink driving. After serving an initial disqualification, offenders can choose to:

  • drive with an interlock device in their vehicle, which requires a negative breath test to start the vehicle; or
  • serve out the remainder of a 5 year automatic disqualification period.

To evaluate the impact of the program, researchers used a dataset of 98,501 proven drink driving and refuse to provide a breath sample offences committed between 1 February 2012 and 30 April 2018, linked to Transport for NSW datasets on MAIP orders and crashes. They compared outcomes for first-time offenders who took up MAIP and who recorded a Blood Alcohol Concentration (BAC) just above the 0.15 threshold, with outcomes for first-time offenders just below the threshold who were likely to have taken the program up were it available. To estimate the program’s overall impact, the researchers also compared outcomes for offenders who committed MAIP-eligible offences with offenders who committed first time mid-, low- or special-range drink driving offences, before and after MAIP was introduced.

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Crime and Justice Bulletin 251