Predictors of commencement and completion of the NSW Mandatory Alcohol Interlock Program

Background

• 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.
  We obtained a dataset of 10,209 interlock orders from Transport for NSW that had an initial disqualification period ending on or before 20 April 2019 and linked these with the NSW Bureau of Crime Statistics and Research’s Re-offending Database (ROD). We used logistic regression to examine factors associated with: a) starting MAIP (for the entire sample); and b) completing MAIP (using 2,860 interlock orders where a person had installed an interlock device and could have completed the program by 20 April 2019). We measured the performance of our models using the Area Under the Curve (AUC).

Key findings

• already disqualified at the time of the offence (15 percentage points less likely to start);
• aged 55 years and above (20 percentage points less likely to start the program than 18-24 year olds);
• Aboriginal (12 percentage points less likely than non-Aboriginal offenders and 15 percentage points compared to those with unknown Aboriginality); or
• sentenced to imprisonment at the index contact (15 percentage points less likely to start).

Most offenders who started MAIP completed the program (91%).

Conclusion