Drivers who use an alcohol interlock are far less likely to drive under the influence again, and this effect continues even years after the programme ends. This is shown by new research conducted by psychologist Martine Blom.
For the first time, there is robust scientific evidence that the Dutch alcohol interlock programme (ASP) is effective in preventing repeat drink-driving offences.
“The results are clear: drivers with an alcohol interlock are less likely to reoffend, not only during the programme but also afterwards,” says Blom. “This suggests that the programme may lead to lasting behavioural change. That is an important step forward for road safety.”
Promising programme discontinued
The ASP was introduced in the Netherlands in 2011 for drivers with a high blood alcohol level. Participants were required to install an alcohol interlock that prevented the vehicle from starting after a positive breath test, and they followed an intensive Monitoring & Support programme with personalised feedback and education. The aim was to prevent repeat drink-driving and encourage lasting behavioural change. Although the programme showed promise, it was discontinued prematurely in 2016 due to legal objections. “It is unfortunate that the programme was stopped at that point, as its effects had not yet been fully examined,” says Blom.
First systematic evaluation
Blom’s research fills this knowledge gap. By linking national data from the Dutch driving authority (CBR) with judicial records, she was able to compare the behaviour of drivers who used an alcohol interlock with similar drivers who did not. The findings show that those who used the interlock committed significantly fewer repeat alcohol-related offences, both during the programme and in the years that followed.
Effective across most groups
The ASP proved effective for men and women, younger and older drivers, novice and experienced motorists, and individuals with different criminal backgrounds. Only a small group of ‘early starters’ – people who had their first contact with the justice system before the age of sixteen – benefited less from the programme and may require a broader, more intensive approach.
Lasting behavioural change
The study shows that the effects of the alcohol interlock are not merely temporary. The combination of technical control and intensive guidance leads to genuine behavioural change. “This does not appear to be a measure that simply restrains offenders for a short period,” Blom explains. “The alcohol interlock helps drivers change their habits, significantly improving road safety.”
Policy implications
The findings offer clear guidance for policymakers. While driving bans are often violated, the alcohol interlock effectively prevents drivers from reoffending while allowing them to retain their mobility. “The results show that reintroducing the alcohol interlock programme could be a targeted and proportionate way to improve road safety,” Blom concludes. By carefully adjusting costs, duration and target groups, the ASP could be implemented in an effective and fair manner.
Martine Blom will defend her PhD thesis on this research on 11 February 2026 at Vrije Universiteit Amsterdam.