A Review of International Evidence on the Use of Alcohol Ignition Interlocks in Drink Drive Offences

  • Published: Department for Transport, Road Safety Research Report No. 89, 2008
  • Authors: A. Clayton and D. Beirness
  • Date Added: 28 Mar 2013
  • Last Update: 28 Mar 2013
  • Format: pdf


To inform understanding of the practical and technical issues, problems, and solutions in implementing large scale interlock schemes.


Evidence review of the international experience regarding implementation of alcohol ignition interlock programmes. Much of the required information was qualitative and not readily available in published documents. Four main techniques were employed:

  • literature review
  • internet review
  • face-to-face discussions
  • case studies

Key Findings:

  • Interlock programmes have been shown to be effective in reducing drink-driving recidivism for both first-time and repeat offenders while the device is installed. However, there is little, if any, residual effect in preventing impaired driving after the device is removed. The main problem with the overall effectiveness of interlock programmes lies with low participation rates.

  • To ensure compliance with the programme, it is essential that the various violations and their associated sanctions are made clear, and that the effective monitoring of participants is implemented. It should be recognised that most offenders will commit some minor violations as they get used to the equipment. By contrast, the level of attempted circumvention in offender programmes is extremely low – often reported as less than 1 per cent.

  • Schemes are costed on the basis of fixed (largely set-up) and variable (mainly participant) costs. Most schemes are based upon the principle of ‘user pays’, with a typical cost of £500 to £800 in North America for a one-year programme.

  • Trends in interlock programmes are towards installing the interlock as soon as possible after the offence, dispensing with any initial period of disqualification, and adopting a criterion-based approach to completing the programme.


Alcohol ignition interlocks, evidence review.


Applicable to Great Britain.