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FactFind: Is Shane Ross right to say his drink-driving bill could save 35 lives?

We take a closer look at the facts surrounding the Minister for Transport’s controversial proposals.

minister-for-transport-shane-ross-is-due-to-appear-before-the-oireachtas-transport-committee-2 Source: Sam Boal/RollingNews.ie

MINISTER SHANE ROSS told the Oireachtas Transport Committee last week that his drink-driving legislation could save 35 lives over the next five years.

The bill would mean anyone caught driving over the legal alcohol limit would get a minimum three-month ban, and has provoked both support and opposition from some quarters.

In this FactFind, we’re going to take a closer look at Shane Ross’s claim about the number of lives the bill could save, as well as some of the statistics on drink-driving in Ireland.

The Facts

The law

As of now:

  • Anyone caught driving with a BAC (blood alcohol content) of 80mg of alcohol or more per 100ml of blood is liable to a six-month ban and a €400 fine.
  • Learner or novice drivers caught driving with a BAC of 20mg-80mg are liable to a three-month ban and €200 fine.
  • Anyone with a full license caught driving with a BAC of between 50mg and 80mg is liable to three penalty points on their license and a €200 fine.

What Shane Ross’s legislation would do, in its current form, is remove the possibility of penalty points for driving between 50mg and 80mg, and replace it with a three-month ban.

Thirty-five lives

Source: TheJournal.ie/YouTube

At the Transport Committee last Thursday, Ross said:

The RSA also established that at least 35 people died in collisions over the period from 2008 to 2012, which involved drivers being found responsible due to alcohol levels at between 21 and 80 [mg/100ml]. Of these, 16 were in the 50 to 80 range.
…So if people ask what good this bill will do, there is the answer. If we could prevent 35 deaths over the next five years, wouldn’t it be worth it?

We asked the Minister’s spokesperson to provide a more detailed rationale for his claim, but we did not receive a response to that request.

Here’s what we think is a reasonable assumption about where that claim comes from:

The Road Safety Authority (RSA) analysed 867 out of 983 fatal collisions between 2008 and 2012, and concluded that:

  • 19 deaths over that five-year period resulted from collisions where a motorist was recorded with a BAC of 21-50mg
  • 16 deaths resulted from collisions where a motorist was recorded with a BAC of 51-80mg.
  • Three people were killed in collisions where a motorist recorded 27-66 mg of alcohol per 100 ml of urine (which is the equivalent of 21-50mg BAC).

We’re not sure why the Minister’s claim related to 35 deaths, rather than 38, given the three deaths associated with urine tests yielding the equivalent of 21-50mg BAC.

The RSA told TheJournal.ie that these figures don’t include deaths where a motorist failed a breath test, but their exact BAC was not recorded, so the figure of 35 deaths is probably an understatement.

Using RSA data on road deaths from 2008-2012, we’ve come up with a rough estimate of 45 as the possible total number of deaths in this category.

You can take a look at the figures and rationale behind that estimate here, but for now we’re going to stick to to the 38 known deaths from incidents where a motorist had a BAC of 21-80mg.

It’s worth noting that 38 deaths represents 4% of the 947 deaths that resulted from the 867 collisions examined by the RSA, from 2008-2012.

Does this mean Shane Ross’s bill would, over the next five years, save a similar number of lives? Not quite.

Gardaí has said there is a crisis of confidence in An Garda Síochána

1. Only 51-80mg is directly relevant

At present, learner and novice drivers caught driving with a BAC above 20mg are already liable to a three-month ban.

The Minister’s bill would not change this, so it’s not sustainable to claim that his bill would have a direct effect on the associated number of deaths.

The only relevant change to the law in Ross’s bill would be to impose a three-month ban (instead of penalty points) for drivers with a full license caught with a BAC of 51-80mg.

For that reason, the focus – in terms of the numbers – should only be on deaths associated with that range of BAC – of which we know there were 16 between 2008 and 2012, not 35.

Those 16 deaths represent 1.7% of the 947 road deaths resulting from the 867 collisions examined by the RSA, from 2008-2012.

(We have roughly estimated that the actual total number of deaths in this category was 19, or 1.8% of the 1,077 total road deaths from 2008 to 2012).

It’s worth pointing out, of course, that while Ross’s bill would not change the penalties for drink-driving other than for driving with a BAC of 51-80mg, there could plausibly be a general deterrent effect on drivers, in the knowledge that being caught driving after even a relatively low level of alcohol consumption, would result in a ban.

2. 100% deterrence or enforcement

The premise of Shane Ross’s claim appears to be that since 35 people are known to have been killed in incidents where a motorist was within a certain BAC range, imposing a harsher penalty (a ban) on driving in that BAC range would prevent a similar number of deaths in future.

As we’ve shown, 38 people were in fact known to have been killed in such incidents, and Ross is in fact only imposing a harsher penalty on driving in the 51-80mg BAC range, which was associated with 16 known deaths.

Even so, it cannot reasonably be assumed that imposing a ban for such driving would eliminate the deaths associated with it.

This calculation appears to be based on an assumption that introducing a ban (in place of penalty points) would be 100% effective in deterring such driving, or would be enforced at a rate of 100%.

This is because the number of deaths associated with this kind of driving is obviously fairly directly linked to how prevalent it is – the less people do it, the less likely it is that deaths will come about from it.

Assuming that the introduction of the ban would prevent all such deaths (rather than simply lower their number) requires assuming that either nobody would do it anymore (100% deterrence) or if they did, they would always be caught by Gardaí, and crucially - before a fatal collision took place, rather than being caught after one (100% enforcement).

As we know, neither of these are remotely reasonable assumptions. An even longer ban (six months) already exists for driving with a BAC above 80mg, but of course, people continue to do it, and associated deaths continue to happen.

However, it is of course likely that increasing the penalty for driving with a BAC of 51-80mg would have some deterrent effect, if enforced, and therefore make it – and the deaths associated with it – less common.

3. The sole contributing factor

90391394_90391394 Source: Mark Stedman

The prediction of saving all 35 (or 16-19) lives in future also depends on an assumption that in the case of all those previous deaths, alcohol was the only contributing factor.

That is to say, that there were not other factors involved which, even without the consumption of alcohol by the motorist, would have resulted in a death.

We know from the RSA’s report on 2008-2012, that there were 330 fatal collisions which were deemed to be alcohol-related. But we also know that in just 28 of these (8.5%), alcohol was deemed to be the sole contributing factor.

The remaining 91.5% of fatal collisions deemed alcohol-related involved some combination of alcohol with other factors such as speed, fatigue, drug use, dark clothing, dangerous behaviour.

So even if the bill were 100% effective in preventing all driving in the 51-80mg BAC range, it’s entirely unreasonable to further assume that the removal of alcohol “from the equation” would have prevented all 16-19 of those deaths.

However, there is ample scientific research showing that even low levels of alcohol impairs driving, and so the presence of alcohol in a motorist can exacerbate other factors, just as other factors exacerbate the presence of alcohol.

Therefore the removal of alcohol from “the equation” is likely to lower the risk of fatal collisions, just as removing excessive speeds, or driver fatigue, for example, would lower that risk.

We asked the RSA how many of the 16 known deaths associated with driving in the 51-80mg BAC range were solely attributable to alcohol, but they did not have that information.

4.  Off the roads

Another difficulty in assuming that a ban (rather than penalty points) would have prevented all these deaths is that being caught drink-driving doesn’t always prevent fatal collisions.

This might seem very obvious, but it has a significant bearing on Shane Ross’s claim.

Let’s assume all the motorists driving at 51-80mg BAC who were involved in the collisions that led to those 16 deaths were legally entitled to drive at that time.

Obviously, some of them may themselves have died in those collisions, but apart from that, and setting aside (if they survived) the potential legal or criminal consequences associated with the collision, at a minimum those drivers would have received a three-month ban.

But that ban wouldn’t have prevented those deaths.

The only way we can be sure that all those deaths would have been prevented if Shane Ross’s bill had been in place, is if every one of those drivers had received penalty points for driving at 51-80mg BAC, in the three months before the collision.

In that instance, the imposition of a three-month ban (instead of the penalty points) would have kept them off the roads at the time the fatal collision took place (unless the driver flouted the ban and drove illegally).

It’s possible that this may have been the case for some of the motorists involved in these fatal collisions, but we absolutely cannot assume it was the case for all of them.

We asked Minister Ross’s spokesperson and the RSA how many of these deaths occurred where a motorist had been given penalty points in the three months before the collision, but neither had that information.

It’s worth pointing out that a three-month ban is the minimum penalty under Shane Ross’s bill. Bans can be extended to six months and more, depending on previous incidents and other factors.

Clearly, a ban keeps a driver off the roads for a certain period of time. Where a driver may habitually drive after consuming alcohol, a ban obviously makes that behaviour even less likely.

Conclusion

90386688_90386688 Source: Eamonn Farrell/RollingNews.ie

It stands to reason that increasing the penalty for a certain behaviour will make that behaviour less likely, if the penalty is enforced, and that it will therefore make its most tragic consequences less common.

So it’s likely that imposing a ban for driving with a BAC of 51-80mg will have some deterrent effect on drivers, it will happen less, and fewer people will die as a result.

How many fewer, we can’t say.

And we can’t say with certainty that Shane Ross’s prediction that the bill will save 35 lives, will not turn out to be true.

We do know that based on his presumed rationale, the figure he should be presenting is 38, anyway.

We know that the claim about 35 lives incorrectly takes into account driving habits that have no direct relevance to his bill.

We estimate that the actual total number of deaths relevant to his bill may be around 19 over the five-year period between 2008 and 2012.

And based on the facts available to us now, it seems logically and statistically untenable to claim that the introduction of Shane Ross’s bill will save that number of lives over the next five years.

For supplementary information on the statistics surrounding alcohol and road deaths, and our estimates of deaths associated with motorists driving in the 21-80mg BAC range, click here.

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About the author:

Dan MacGuill

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