The dangers of excessive drink-drive laws

Posted on December 16, 2015

A new report commissioned by the RAC Foundation and the Parliamentary Advisory Council for Transport Safety (Pacts) claims that 25 lives per year could be saved by cutting the drink-drive limit in England to bring it into line with Scotland. But such a claim must be, at best, educated guesswork and takes no account of the harm caused by making the law even more draconian.

The report, Saving Lives by Lowering the Drink-Drive Limit, was produced by Richard Allsop, emeritus professor of transport studies at University College London. There have been a number of studies looking at the relative risk of being in an accident for different levels of blood alcohol. From these, Allsop concludes that the risk of being in any kind of accident at the current English drink-drive limit, 80mg per 100ml of blood, is 5.6 times higher than for someone without alcohol in their blood. The risk of being in a fatal accident is 12.4 times. For those driving at the new limit now widely used across Europe, including most recently Scotland, the risk of any accident is 2.6 times higher and the risk of a fatal accident is 5.0 times higher.

So it is no surprise that drinking with more alcohol is riskier. But riskier than what? This is where some perspective is required - because driving is astonishingly safe. Government road accident statistics for Great Britain suggest that in 2014 there were 1,775 deaths and 22,807 people hurt seriously enough to require hospital treatment, though not necessarily as 'in-patients'. That should be set against the 311 billion vehicle miles travelled by all motor vehicles in 2014.

In other words, one death every 175 million miles travelled and one serious injury for every 13.6 million miles travelled. Even with a risk of fatality 12.4 times, a back-of-a-beermat calculation suggests that someone at the current drink-drive limit would have a fatal accident once every 14 million miles. If you multiply a tiny absolute risk by a big enough number, it is possible to come up with a 'lives saved' number that sounds significant. But in truth, even when driving at the current legal limit, driving is - in common sense terms - still very safe.

And there is the potential for confounding factors here, too. The kind of people who are willing to get into a car after two or three drinks are likely to be more confident and risk-taking than those who stop after one. So their driving behaviour may be different in other ways apart from the effect of alcohol. Of course, there is the genuinely risky minority of people who couldn't give a damn about drink-drive limits and will happily speed around while two or three times over the limit, whatever it is. And we should remember that the most likely people to die in an accident are pedestrians. Taking people out of their very safe cars and forcing them to walk more must increase the risk of fatalities, too. As another government report notes: 'In 2013, 67 per cent of pedestrians who died in road accidents “overnight” (between 2200 and 0359) were over the legal alcohol limit for driving.'

Surely if we can make these very small risks even smaller, that's a good thing? But deciding on any policy must take account of all the potential consequences. Lowering the limit will put many people off driving to the pub at all, even for a single drink, just in case they unwittingly go over the limit. That means pubs that depend on people driving to them will suffer at least some fall in trade. Moreover, there would in the future be a group of people banned from driving after being caught at a level between 50mg per 100ml of blood and 80mg per 100ml. In other words, people will lose the right to drive one year that would not have done if caught the previous year. What are the damaging consequences of that? Road safety campaigners appear to be blind to such consequences which can seriously affect people's livelihoods, future driving costs and much more.

In all of this, a sense of proportion is required. Do the tiny benefits of reducing the risk of an accident by lowering the drink-drive limit outweigh the serious damage to both drivers and non-drivers? We believe the current drink-drive limit is a better balance between these various risks than the lower limit in place in Scotland.