Drink Driving & The Blood Alcohol Limit

About every 3 months (e.g. see here) for the last 10 years, a story has appeared in the papers that goes pretty much like this:


Under the plans, the limit would fall from 80mg of alcohol per 100ml of blood to 50mg. Anyone caught above the new limit would face an automatic 12-month driving ban, even if they were only marginally over the threshold.

I should point out, this is the first time we’ve heard this story since Philip Hammond lauded the end of the war against motorists.


So, with that in mind, let’s have a look at the basis of this urgent and draconian requirement. The drink driving an accident stats that must have been rising at some rate in order to precipitate this move.

• In 2008, it was estimated that 13,020 reported casualties (6 per cent of all road
) occurred when someone was driving whilst over the legal alcohol limit.

• The provisional number of people estimated to have been killed in drink drive accidents
was 430 in 2008 (17 per cent of all road fatalities), an increase of 20 fatalities compared
to 2007.

• The provisional number of KSI (killed or seriously injured) casualties in 2008 was 2,060,
less than a quarter of the 1980 level and 5 per cent below the 2007 level.

• Provisional figures for the number of slight casualties in 2008 fell 7 per cent since 2007,
from 11,850 to 10,970.

Not exactly dramatic, is it? Let’s look at the pretty picture:


Errr.. okay. So why target alcohol in this way?

Let’s have a look at some of the other causes of road accidents that might perhaps warrant some attention.

Here’s the table – click to enlarge, and I’ll pull a few key stats out below.


Of ALL accidents in the reported 12 month period (right hand column):

  • 5% were caused by impairment by alcohol.
  • 1% were caused by drugs (illicit or medicinal)
  • 2% were caused by a distraction inside the vehicle (kids, phones etc?)

So far so good. Now to the point.

  • 14% were caused by performing a poor turn or manoeuvre.
  • 37% were caused by a failure to look properly.
  • 19% were caused by a failure to judge other person’s path or speed.

Well there we are then. Right there are a load of causes we could do something about, under the heading Poor or incompetent driving.

I despair at the continuous fiddling at the edge which impacts on us all, when some straightforward measures could have a massive impact.

Next, let’s have a look at the trends in these causation statistics. Again, click to enlarge.


Caused by failing to look properly – percentage.

  • 2005 – 32%
  • 2006 – 35%
  • 2007 – 35%
  • 2008 – 37%

See that? The increase in accidents caused by failure to look properly? Over 4 years that delta is equal to the absolute proportion caused by alcohol.

Caused by failing to judge other person’s speed or path – percentage.

  • 2005 – 18%
  • 2006 – 18%
  • 2007 – 18%
  • 2008 – 19%

Oh – hey – a 1% rise. And 1% is the total proportion of accidents caused by legal and illegal drugs.

Now if only they could break down those failing to look and failing to judge figures by gender. That would be interesting.

In the meantime, ConDems. Shelve this shit and keep your promise to get off our backs, eh?


UPDATE: The Telegraph article points to a suggestion that [weasel word alert] the number of fatalities could be cut be up to 168 a year.

In other words, this report reckons that nearly 40% of drink-driving deaths in 2008 were caused by drivers in the margin between the current 80mg and proposed 50mg limit.

I’ll be interested to know how that estimate was arrived at.

UPDATE 2: Actually, it’s worse than I stated above. The report referred to in the Telegraph, gives the 168 figure for England and Wales only. The Figure of 430 deaths (killed due to alcohol impared driver/rider) refers to Great Britain, so you need to take the Scottish figures (~30 per this) away from the 430.

This pushes the estimated percentage of fatalities caused by drivers in the margin between the current 80mg and proposed 50mg limit much closer to 50%.

To see how badly this figure doesn’t stack up, we’ll now refer to table 3d (p.38) in the “Reported Road Casualties Great Britain: 2008”. Click to enlarge.


Of motorcycle riders, in 2007:

13% of those killed had more than 50mg of alcohol/100ml of blood.

11% of those killed had more than 80mg of alcohol/100ml of blood.

In other words, 2% of those motorcyclists killed had blood alcohol levels between the existing and the proposed levels.

Of drivers, in 2007:

24% of those killed had more than 50mg of alcohol/100ml of blood.

22% of those killed had more than 80mg of alcohol/100ml of blood.

In other words, 2% of those drivers killed had blood alcohol levels between the existing and the proposed levels.

This seems to give the big fat whopping lie to the estimated reduction of 40% or more, sold by report author Sir Peter North, the former Principal of Jesus College, as the pay off for this reduction in the limit from 80mg to 50mg.

Disclaimer: I’m not a statistician, so my figures are inevitably somehow flawed, but I don’t think they’re a million miles off.


6 thoughts on “Drink Driving & The Blood Alcohol Limit

  1. On reading other related statistics I note:

    “It is worth noting that whilst the driver/rider may have been impaired, these statistics are not concerned with the influence of alcohol/drugs as a contributory factor in these collisions”.

    I can only assume that some of the unfortunate 2% are actually killed by the 37%.

    Of my 5 (stone cold sober) motorcycle accidents 80% of them were due to the “I didn’t see you mate” brigade.

    Thanks for the research.


  2. Great article, Al.

    More inane tinkering for no fucking reason but because they can.

    There are one or two daft proposals like this coming up soon which will prove to us if this coalition means what it says, or are just a different bunch of authoritarian bastards passing laws which have no benefit but huge downsides.

    If it’s the latter, they should be jumped upon from a atmospherical height.

    • indeed – pinged the Q as to whether there’s an EU directive in force on the 50mg limit over to IanPJ.

      He tells me there isn’t, but “there is an ‘Opinion of the Commission’. Govts must work towards that or face a directive.”

      So indeed you are correct, and we can expect the report recommending this change to be another fine example of policy-based evidence-making.

  3. To be fair, this is only the report commissioned by the previous government that has now been completed by Sir Peter North and submitted to the new government – it doesn’t mean that they will definitely implement it. But, if they have a single ounce of sense and decency they should, as you say “Shelve this shit and keep your promise to get off our backs, eh?”

    The consultation paper on the issue produced in the late 1990s said that cutting the limit would probably reduce annual road fatalities by about 50, and even that seemed to be based on the assumption that every single fatal accident involving a driver in the 50-80 range was caused by alcohol, which is clearly nonsense.

    Another sinister proposal included in the Telegraph report is making it an offence to drive with an illegal substance in your bloodstream – without any need to demonstrate impairment. So you have a spliff, you’re caught driving ten days later and end up getting banned. Wow!

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