Alcohol Interlock Implementation in the European Union; Feasibility study

Final report of the European research project
Bax (SWOV, ed.), Charlotte ; Kärki (VTT), Otto ; Evers (BASt), Claudia ; Bernhoft (DTF), Inger Marie ; Mathijssen (SWOV), René

From 1 November 2000 until 1 September 2001, a consortium of European road safety research institutes conducted a feasibility study regarding the implementation of Breath Alcohol Ignition Interlock Devices (BAIIDs) in EU drink-driving policies. A BAIID is a breath testing device connected to the ignition system of a motor vehicle. It prevents an operator from starting the vehicle if the breath alcohol concentration (BrAC) exceeds a predetermined threshold or fail level. The use of BAIIDs is embedded in a program of monitoring and servicing, sometimes complemented with medical and/or psychological interventions.

In more detail, the goals of the study were:

  • to investigate the effects of BAIID use on drink-driving and road safety;
  • to identify target groups for BAIID programme participation;
  • to make an inventory of the requirements BAIIDs and programmes should meet;
  • to design an EU field trial;
  • to identify EU countries which are willing and able to introduce BAIID programmes.

The effects of BAIID programmes on drink-driving and road safety

Over the last 15 years several American and Canadian BAIID programmes for DUI (driving under the influence) offenders have been evaluated. Despite huge differences among the programmes, the target groups and the accompanying evaluation studies, study results indicate that BAIIDs effectively prevent drink-driving during the period of BAIID installation. Most studies, however, give proof of methodological inadequacies which make the results less conclusive. In only one study, in Maryland, multiple DUI offenders were randomly assigned to the experimental or the control group. Preliminary results indicated that, within the first year of BAIID programme participation, DUI recidivism was reduced by about 65% (Beck et al., 1999).

According to most studies, after BAIID removal from the vehicle recidivism rates appeared to increase again. No residual effect in preventing impaired driving could be observed. An exception is preliminary data from a BAIID programme in Quebec, which started in 1997. The study design was that of a before-during-after comparison. No control group was included in the study. During the period of BAIID installation, the DUI recidivism rate dropped by more than 90%. In a six-month period following removal of the BAIID, the recidivism rate did not increase. Furthermore, traffic offence and crash figures showed a significant decrease during both the BAIID- and after-periods (Dussault & Gendreau, 2000).

Preliminary results from a study in Calgary and Edmonton (Alberta, Canada) suggest that the incorporation of rehabilitation (‘harm-reducing intervention') in the BAIID programme has positive effects on recidivism rates after the BAIID period. This finding, however, was not statistically significant. The rehabilitation programme was designed to educate and raise awareness among participants of the need to plan and re-evaluate their vehicle use whenever alcohol consumption was likely to occur. The participants met with a case manager every time the BAIID needed servicing.
Furthermore, statistical analysis showed that programme participants with high failure rates during the BAIID period were 2-3 times more likely to commit a re-offence after the BAIID period. This result suggests that participants with high failure rates should be required to have an interlock for an extended period (Marques et al., 2000).

The promising results of the American and Canadian evaluation studies justify a large-scale field trial in one or more EU countries.

Target groups for an EU field trial

In the United States, Canada and Australia, targets groups of BAIID programmes were first offenders with very high alcohol concentrations, second offenders and multiple offenders. In Sweden, target groups also include professional drivers and alcohol-dependent drivers.

Due to a great variety in sanctions for driving under the influence of alcohol in the various EU countries, it is not feasible to define one or more target groups for an EU field trial in terms of offender types, like first, second or multiple offenders. A definition in terms of imposed sanctions for DUI seems to be more appropriate. In that case, the definition of target groups could be related to the sanctions of license suspension (imposed by the court) and/or mandatory rehabilitation/driver improvement courses (imposed by the licensing authority). Participation of alcohol-dependent drivers does not seem possible without a change in legislation in the participating countries.
Possible target groups for commercial BAIID programmes are tour operators, (local) bus companies, dangerous goods or heavy freight transport companies, and taxi companies. The actual use of the BAIIDs by the drivers involved should, of course, be compulsory.

The greater the drink-driving problems of the target group are, the greater the beneficial effects on road safety can be. Therefore, DUI offenders seem to be the most appropriate target group for an EU field trial.

EU BAIID programme requirements

Technical requirements

The BAIID will have to meet certain technical requirements. Technical standards have been defined in the USA, Canada and Australia. These standards relate to reliability, accuracy, circumvention and tampering, and electromagnetic interference with the vehicle and vice versa. The most recent and most demanding standards are the Alberta standards, which also apply in Sweden.
In order to minimize the risk of false positive readings, BAIIDs with an electrochemical sensor (fuel cell) are recommended. Key features to prevent circumvention or tampering are: sealed wiring, human breath recognition systems, the inclusion of a data recorder, and random running re-tests.

Ideally, technical requirements should be uniform for all EU countries. Furthermore, they should meet the highest possible technical standards, these for the moment being the Alberta standards. But, on the other hand, very high standards may cause lack of competition between manufacturers, thus increasing the cost of the devices. To date, only one device meets the Alberta standards. The cost of the device may strongly influence a DUI offender's willingness to participate in a BAIID programme. So, in order to stimulate competition, it might be sensible to allow some variation of the technical requirements between EU countries, depending on their topographical and climatic conditions. It does not seem necessary for all EU countries that the devices function accurately up to a height of 3,500 metres or within a temperature range of -45 to +85 °C.

Not all technical requirements, however, are covered by existing standards. In the literature on BAIIDs nothing was found, for instance, on the subject of an emergency bypass switch. Whether BAIIDs should be provided with such a switch, depends on the risk of false positive readings and other kinds of malfunction. During preliminary testing by one of the consortium partners, the connector of the detachable sample head broke down, preventing the car from getting started. Therefore, it seems advisable to install an emergency bypass switch in the vehicles involved in an EU field trial, and to evaluate legitimate and illegitimate use.

Bypassing the BAIID should be considered to be a programme violation, except when the driver can prove force majeure. The bypass switch should allow for single-use, resulting in a compulsory visit to the service provider within a few days. Otherwise, the car should be immobilized.

A primary safety criterion that BAIIDs will have to meet, is that running re-tests can be performed without visual distraction and/or unintended manoeuvring. This implies, among other things, the following technical requirements:

  • The sample head has to be mounted in such a way that it can be used and replaced without the driver having to take his eyes off the road or to change his position behind the steering wheel.
  • The request for a running re-test and the sampling procedure should only be accompanied by unambiguous auditive signals, and should not interfere with the driving task.

In addition to these requirements, training of all BAIID users in real traffic or in a simulator is recommended.

Implementation procedures

An important item is the setting of a BrAC threshold (fail level) for BAIIDs. The main goal of a BAIID programme should be that participants learn to separate drinking from driving. For that reason, a BrAC threshold of 0.00 mg/l would be preferable. On the other hand, the breath testing device may produce small positive test results, even if a person has not drunk alcoholic beverages. So, for practical reasons and for the sake of legal security, a BrAC-threshold of 0.10 mg/l is recommended. Depending on the national legislation of EU countries, this threshold equals a blood alcohol concentration (BAC) varying from 0.21 to 0.23 g/l.

BAIID programme participation can be administered under criminal law (by the courts) or under administrative law (by the licensing authority). Participants should be monitored regularly, and simultaneously the data from the BAIID data recorder should be reviewed. Monitoring and enforcing a DUI offender's compliance with the BAIID programme requirements demands close co-operation between programme providers, the police and the programme administrative authority (probation or licensing authority).

It is recommended that DUI offenders pay at least part of the cost of BAIID programme participation in order to get a motivated participant group. On the other hand, too high costs may be a barrier for eligible DUI offenders to participate.

Legal requirements and existing provisions in EU countries

A survey of legal requirements and provisions for BAIID programmes was conducted in eleven European countries. Although, apparently, legal aspects had not yet been thoroughly investigated by the respondents, the following essentials could be derived from the survey results:

  • BAIID programmes can be integrated in existing sanctions for DUI. They can, for instance, substitute license suspension or shorten the suspension period, or they can be implemented as an accompanying measure as part of rehabilitation/driver improvement courses.
  • BAIID programmes can be introduced as a general preventive measure (for all volunteering drivers, for various categories of professional drivers, etc.) or as a specific preventive measure (for DUI offenders).
  • BAIID programmes for DUI offenders should, at least partly, be financed by the participants.
  • Suggested BrAC thresholds (fail levels) varied from zero to the legal limit.
  • Mandatory BAIID programmes are assumed to require changes in legislation, especially in traffic law.
  • The predominant opinion of the respondents is that BAIID programmes constitute an effective tool in preventing drink-driving, and a good alternative for license suspension.

Design of an EU field trial for DUI offenders

Target groups

The definition of target groups can be related to the sanctions of license suspension (imposed by the court) and/or mandatory rehabilitation/driver improvement courses (imposed by the licensing authority).

Under criminal law, the following DUI offenders might be target groups for BAIID use:

  • DUI offenders who, if the sanction of mandatory BAIID programme participation did not exist, would have only a period of probationary license suspension imposed by the court. For these offenders, the mandatory BAIID use would mean an aggravation of the sanction, which in most EU countries would probably require an amendment of the law.
  • DUI offenders who, if the sanction of mandatory BAIID programme participation did not exist, would have a period of hard license suspension imposed by the court. For these offenders, the mandatory BAIID use would mean an alternative sanction: (part of) the hard license suspension period is replaced by a probationary license suspension period, combined with mandatory BAIID use. If the court leaves the choice between hard suspension or participation in a BAIID programme to the discretion of the offenders, the programme is quasi-voluntary. Participation rates will then probably be (much) lower than in the case of fully mandatory participation. At least in some EU countries, participation in a BAIID programme can be imposed without an amendment of the law.

Under administrative law, mandatory BAIID use might be imposed on all drivers who have to follow a rehabilitation/driver improvement course as a condition for license re-instatement. For these drivers, too, the mandatory BAIID use would mean an aggravation of the sanction. In which countries this would require an amendment of the law, has not become very clear from the inventory of legal requirements and possibilities, probably reflecting the fact that these have not yet been considered in detail.

Most desirable versus most realistic target group

The most desirable target group is constituted by drivers who have to follow a rehabilitation course, since the effectiveness of BAIID use will probably be enhanced, if it is combined with rehabilitation. Furthermore, the effectiveness of rehabilitation courses will probably also increase, by combining them with a BAIID programme. There seem to be some major practical problems, though. Some of the drivers who have to follow a rehabilitation course, may have had a period of hard suspension and/or a period of mandatory BAIID use imposed by the court, which might interfere with BAIID use as part of a rehabilitation course. The most realistic target group for an EU experiment is probably that of DUI offenders who have had a period of mandatory BAIID use imposed by the courts, as an alternative for a period of hard license suspension. If these drivers also have to follow a rehabilitation course (and in some EU countries this will be the case for nearly the entire group), it is recommended to find ways of combining the two.

In order to stimulate BAIID programme participation by DUI offenders, it is recommended to avoid a preceding standard hard suspension period. Firstly, because the offender's financial position might deteriorate dramatically as a result of hard suspension; for commercial drivers it can even constitute grounds for dismissal. And secondly, because a suspended DUI offender might still drive a car and perceive a very low risk of apprehension. In both instances, the cost of BAIID use might exceed the perceived benefit. This may especially be important, if an offender is given the choice between a period of hard suspension or entering a BAIID programme. Therefore, preceding hard suspension periods should preferably be restricted to very serious DUI cases.

Duration of an experimental BAIID programme

The period of BAIID use to be imposed by the court, might be linked to the period of probationary license suspension that it is combined with, for instance:

  • As an alternative for 3 months of hard suspension: 6 months of probationary suspension in combination with 18 months of BAIID use.
  • As an alternative for 12 months of hard suspension: 3 months of hard suspension + 12 months of probationary suspension in combination with 24 months of BAIID use.

The prolonged periods of probationary license suspension in the case of BAIID programme participation might give in to objections from some EU countries against replacing or mitigating the existing sanction of hard license suspension.

If BAIID programmes become an integrated part of rehabilitation courses under administrative law, they can probably be better tailored to individual participants. Also, pre-conviction programme participation would be possible. A practical problem, however, would occur if, in a later stage, the court imposed a period of hard suspension.

Evaluation of an EU BAIID experiment

The design of an experimental BAIID programme for DUI offenders should be aimed at evaluating the effects on DUI recidivism and, if possible, accident rates. Based on the results of the latter evaluation, a cost-effectiveness analysis could be made.

The experimental group might consist of DUI offenders who have had a BAIID programme imposed or offered by the courts, as an alternative for hard license suspension. An important advantage of taking this entire group instead of the subgroup that is actually participating in a BAIID programme, is that the problem of self-selection is avoided.
The control group should then consist of DUI offenders who have had a hard suspension period imposed. Random assignment to experimental or control groups would be ideal, but is probably not feasible since it would create a high degree of legal inequality between equal offenders.
If random assignment is not possible, the control group might be found in an area where the alternative of BAIID programme participation is not available. In that case, it is important that the control group comes under the same (national) jurisdiction as the experimental group. Otherwise, both groups may very possibly not be not comparable with respect to the severity of their drink-driving offences and their risk of repeat drink-driving. Furthermore, the risk of apprehension for DUI should be more or less identical for both groups. This so-called ‘post-test-only design with equivalent groups' is probably feasible, since the inequality between DUI offenders in the experimental and control area is not of a legal but of a physical nature (namely depending on the availability of a BAIID programme). The design could be strengthened by including a pre-test period. This is possible by collecting data on DUI offences and accident involvement over a period preceding BAIID programme participation or license suspension.

In order to get convincing results for both policy makers and the general public, the experimental group should contain at least 500 actual BAIID programme participants; the control group might contain approximately 1,000 DUI offenders who have had a period of hard license suspension imposed. From a statistical viewpoint, this sample size allows a recidivism reduction of approximately 30% in the experimental group, when compared to the control group, to be significant at a 95% probability level.

Recidivism rates should be compared both during and after treatment in order to assess the long-term effects, preferably by means of survival analysis. This kind of analysis makes it possible to account for competing hazards, like hospitalisation, death or imprisonment of the drivers involved.

If the experimental group consisted of DUI offenders who are following a mandatory rehabilitation course with integrated BAIID use, the control group would consist of DUI offenders who are only following a mandatory rehabilitation course. On this design the same conditions with respect to comparability of the two groups are applicable as in the design for DUI offenders who have had a BAIID programme imposed or offered by the courts.

Duration of an EU BAIID experiment

The duration of an EU experiment with BAIID use by DUI offenders would be approximately 4½ years:

  • inclusion period: ½ year;
  • experimental period: 2 years;
  • post-experimental period: 1 year;
  • data collection, analysis and reporting: 1 year.

If a rehabilitation course is integrated in the BAIID programme, extension of the post-experimental period with one year may be interesting. That is, if the reduction of recidivism during programme participation was significant. In that case, reporting might be split into two parts: after 3½ years on the effect during programme participation, and after 5½ years on the effect after programme participation and BAIID removal from the vehicle.

Feasibility of an EU BAIID experiment

In order to identify countries which are able and willing to undertake a field trial, the research consortium not only conducted the before mentioned survey among road safety experts of various EU countries, but also organized an international workshop on BAIIDs.
Representatives of Belgium, France, the United Kingdom, the Netherlands, Spain and Finland expressed their interest in conducting a BAIID field trial, some of them not necessarily in an EU context. Most countries, however, were not yet aware of the details of the required legal, practical and financial arrangements.
Due to the great variety in sanctions for driving under the influence of alcohol in the various EU countries, it would be an advantage if an experiment could be conducted both in a country with relatively light DUI sanctions (target group of relatively severe offenders) and in one with relatively severe sanctions (target group of relatively light offenders). A significant reduction of DUI recidivism among severe offenders, however, will be more beneficial for road safety than a reduction among light offenders. Furthermore, a comparison between BAIID programmes with and without integrated rehabilitation would be useful.
The research consortium of the feasibility study recommends that the European Commission appoints a follow-up co-ordinator to whom trial proposals and grant applications can be submitted. In Annex 12 of the report, a list of proposed minimum standards for an EU field trial has been included.

84 + 77 p.
Gepubliceerd door
SWOV, Leidschendam


Dit is een publicatie van SWOV, of waar SWOV een bijdrage aan heeft geleverd.