Evidence to the Transport Committee`s Inquiry into Drink & Drug Driving Law

August 2010



1. The Association of British Drivers (ABD) was formed in 1992 to campaign for a better deal for Britain`s motorists. The ABD believes that laws affecting drivers should be reasonable and enforcement of them should be fair and proportionate.

2. The ABD is a voluntary organisation funded by subscriptions and donations from its members and supporters. It receives no funds from public bodies or large corporate donors, so is truly independent. The ABD is a member of the Parliamentary Advisory Council for Transport Safety and the National Council of Voluntary Organisations.

3. Many of the ABD`s active members are from professional or managerial backgrounds. Malcolm Heymer, who is submitting this evidence on behalf of the ABD, holds a master`s degree in Transportation Engineering and has over thirty years` local government experience in the fields of transportation modelling, highway engineering, transport planning and traffic engineering. Mr Heymer is willing to give oral evidence to the Committee if requested.

4. The following sections of this submission address the questions raised in the call for evidence as a result of Sir Peter North`s report.

Permitted blood-alcohol limit for driving

5. The ABD believes that the current limit of 80 mg of alcohol per 100 ml of blood is the best compromise between deterring irresponsible behaviour and unnecessarily penalising drivers who present a very low risk. The ABD does not condone drinking and driving, and supports the advice that ideally drivers should not drink at all if they plan to drive. The ABD opposes a reduction in the legal limit, however, partly because it would cause more responsible drivers to fall into the morning-after trap. The current limit also has widespread support, with little sympathy for those caught in excess of it. This could change if the limit were reduced.

6. In November 2008 the Department for Transport published a consultation on road safety compliance, which included a section on drink driving. Table 3.2 of the consultation paper (reproduced below) showed that just 1% of drivers and riders killed in road accidents had a blood-alcohol concentration (BAC) in the range 50–80 mg. The figure was 2% in the range 80–100 mg and rose substantially at higher levels. The fact that a driver had some alcohol in their system does not necessarily mean that this was the cause of their accident, since they could have been the innocent victim of another road user`s error or bad driving. There is always more than one contributory factor in any accident.

Table 3.2 Percentage exceeding various blood alcohol levels; and proportion of fatalities exceeding 80mg/100ml by time of day
 Percentage exceeding each blood alcohol level band (mg/100ml) Percentage over 80mg/100ml at time shown
200+200–150150–100100–8080–50Sample size22:00–03:5904:00–21:59
Motorcycle Riders4%5%2%1%1%44740%9%
Other vehicle drivers11%8%6%2%1%84853%17%

7. In February 1998 the former Department of the Environment, Transport and the Regions (DETR) published a consultation document on combating drink driving. In Annex 1 to that consultation, reference was made to roadside surveys conducted at various sites around Britain between 1988 and 1990. These showed that 2.3 per cent of drivers tested (i.e. a sample of all drivers, not just those suspected of drinking) had a BAC in the 40–80 mg range. Reference was also made to a study of road accident victims attending the John Radcliffe Hospital, Oxford, during the same period. This showed that 2.1 per cent of drivers treated had a BAC in the 50–80 mg range. These figures suggest that the proportion of drivers involved in accidents with a BAC level between 50 and 80 mg is much the same as that of the driving population as a whole, indicating that there is no perceptible increase in risk at this BAC level.

8. Since Table 3.2 shows rapidly growing percentages of drivers killed as BAC levels exceed 100 mg, there can be little doubt that alcohol is more likely to be the main contributory factor as BAC levels rise. The figures given in the earlier DETR consultation suggest there would be a negligible impact on accidents if the limit were reduced to 50 mg. The main problem is clearly caused by those who exceed the current limit by a substantial margin, so this is where action should be targeted.

9. The North Report (paragraphs 3.29 to 3.32) claims very high increases in the risk of being involved in a fatal accident at BAC levels well below the current legal limit: three times greater for a BAC in the 20–50 mg range compared with a driver with no alcohol and six times greater in the 50–80 mg range. These figures are derived from a 1991 study by the Transport Research Laboratory (TRL 232). As recognised in the North Report, this study had its limitations and was much smaller than the ‘Grand Rapids` 1964 study on which the current legal limit of 80 mg per 100 ml of blood was based. The latter showed a risk increase of no more than 1.5 times at the 80 mg level.

10. The very high risk factors quoted in the North Report are at odds with reported BAC levels in fatal accidents and are intuitively not credible, otherwise moderate drinkers would be more heavily represented in the accident figures. In practice, most responsible drivers do not attempt to drink up to the BAC limit, as they have no way of measuring their BAC and there are so many unknowns that affect the way an individual absorbs and processes alcohol. Consequently they leave a wide margin for error.

11. A lower limit would make responsible drivers more vulnerable to the morning-after trap, when they have avoided driving while drinking the night before but could still be over the limit the following day. There is evidence that, for a given BAC, a driver is more impaired when the level is rising than when it is falling. The following comes from Loosening the Grip: A handbook of alcohol information by Kinney and Leaton (ISBN 0-8016-2769-9, page 42 in the 1991 edition):
“The neurophysiological basis for intoxication is not fully understood, but the intensity of the effect is directly related to the concentration of alcohol in the blood, and hence the brain. The degree of intoxication is also dependent on whether the blood alcohol level is rising, falling, or constant. It is known that the central nervous system and behavioural effects of a given blood alcohol concentration (BAC) are greater when it is rising. This is called the Mellanby effect. It is as if there were a small ‘practice effect` or short-term adaptation by the nervous system to alcohol`s presence. Thus for a given blood alcohol level, there is more impairment if the blood level is rising than is found with the same BAC when the level of alcohol in the blood is falling.&rdqou;
12. Consequently, a driver might feel, and be, safe to drive the next morning while still having an illegal level of alcohol in their blood. Drivers prosecuted for having a BAC in the 50–80 mg range in these circumstances might feel they have been treated unjustly, and this could weaken support for the drink-driving laws. While no fixed limit for BAC can ever exactly match the level at which significant impairment begins in different individuals, the current limit has the virtue of being based on a large-scale study in the 1960s and is generally accepted as reasonable. This is important and the current limit should not be reduced unless strong evidence emerges that a lower limit would prevent a significant number of accidents. No credible evidence to that effect appears to exist at present.

Punishment of drivers with low blood-alcohol levels

13. If the blood alcohol limit were reduced, which the ABD hopes will not happen, it would certainly be necessary to impose a lower penalty for drivers in the 50–80 mg range. Removal of the mandatory driving ban would be essential to avoid unduly harsh penalties for those representing very little risk. If the current mandatory one-year ban were retained for drivers with a BAC in this range, it would be disproportionate and at odds with the practice in most other European countries. The law could quickly fall into disrepute.

14. Some other countries operate a sliding scale of penalties according to the degree to which a driver exceeds the legal alcohol limit. This more flexible approach would be beneficial in the UK, especially if the blood alcohol limit were lowered. It is right that extreme offenders should be treated severely, but those posing little risk should face lower penalties.

The problem of drug driving

15. The ABD accepts that drug driving is a more difficult problem to tackle than drink driving, since many substances, both legal and illegal, may be involved and taken singly or in combination. The existing law may be difficult to enforce, therefore, on the basis of subjective tests of impairment.

16. It would not be acceptable, however, in the interests of securing easy convictions, to introduce a law that made it an absolute offence to drive with any trace whatsoever of an illegal drug, if there was no evidence of actual or likely impairment at the measured blood level. Traces of some drugs, notably cannabis, can be detected long after any impairment effects have disappeared. While the use of illegal drugs should be discouraged, this worthy aim must not be pursued by punishing drivers who are not causing actual danger.

17. Given the speed with which new ‘designer` drugs can be developed, a list of proscribed drugs will quickly become out of date. Efforts should be concentrated, therefore, on developing better ways of assessing impairment at the roadside or in a police station to enable those who present a real danger to be dealt with effectively.

Costs and benefits of changes to drink and drug driving law

18. As explained above, the ABD considers there would be very little benefit from a reduction in the legal blood-alcohol level for driving, since it would be unlikely to have a significant effect on casualties. It would, however, be likely to lead to more convictions of responsible individuals caught in the morning-after trap, which would cause resentment and bring the law into disrepute.

19. The wider implications would most probably include an accelerated rate of closure of public houses in rural areas, with detrimental economic and social consequences for those communities. Paradoxically, rather than reduce drinking overall, a lower limit could cause more people to stay at home and drink cheap alcohol from supermarkets rather than drink responsibly in the more controlled environment of public houses.

20. The development of better impairment tests for drivers suspected of drug-driving could help address this apparently growing problem, especially among the young. The creation of new, absolute offences, however, could lead to needless and unfair prosecutions, undermining respect for the law.

Implications for enforcement

21. Whether drink and drug laws are changed or not, there needs to be a sufficient police presence on the roads to act as a deterrent, which is more important than detecting offences once they are committed. The ABD believes the police have adequate powers to stop anyone they suspect of drink or drug driving, so there is no need for a specific power to carry out random testing. Indeed, if random testing were allowed, it is likely that police resources would be wasted in carrying out tests on innocent drivers when they should be targeting those showing clear signs of impairment.

22. Police patrols have been reduced in many parts of the country in recent years, as the number of speed cameras has increased. Cameras cannot, of course, detect drink or drug driving (or many other driving offences), so there is an increased perception by those tempted to flout the law that they are unlikely to be apprehended. With the current constraints on public spending, it is increasingly important that available resources are targeted to greatest effect. There are welcome signs that many local authorities are reducing their expenditure on camera enforcement, which has mainly detected technical offences, so it is to be hoped that the tide is turning in favour of a greater police presence to tackle behaviour that is actually dangerous.