Drink Driving in Scotland – Problems When the Law Outpaces Technology

Traditionally, the law is subject to much criticism and commentary for being unable to keep up with the rapid advancement of technology.

However, the introduction of the new drink driving limits in Scotland have seen quite the opposite. The law in this area has advanced, yet the technology used to record drink drive readings has stayed the same –inaccurate.

This poses a problem for the law in terms of prosecutions, in that they can subject to challenge on the basis of the accuracy of  breathalyser technology in marginal cases.

But, why wasn’t this a problem previously? And should the law impose strict limits when the technology used can’t provide accurate evidence?

Why is out of date technology a problem for the new law?

Prior to the new drink driving limits being introduced, the drink drive limit for a breath sample was 35 micrograms of alcohol per 100 millilitres of breath. However, due to the inaccuracy of the technology used to take the breath sample, a margin of around 5 micrograms was afforded. This meant that effectively, readings of less than 40 micrograms were not prosecuted. This remains the case in England and Wales.

This margin for technological error is as a result of an agreement between Crown Agent and the Law Society of Scotland, presumptively to avoid a high level of challenges to drink driving convictions in cases where the reading is within the ambit of technological error.

The introduction and testing of breathalyzer technology introduced in the 1980’s demonstrated that machines would provide variable readings when tested with a simulated breath sample of the same level of alcoholic volume. A range was agreed in relation to these readings and consequently, those who were marginally above the drink drive limit were not to be prosecuted.

The Crown Prosecution Service in England and Wales have published clear guidance on this policy on their website and this still remains the law in these countries.

However, the new limit of 22 micrograms includes no such margin. This was uncovered by legal news and advice resource Unlock The Law last this week after consultation with the Law Society. They were advised by the Law Society that where there is clear and reliable evidence in support of a drink driving charge the Crown will bring a prosecution. The decades old agreement will no longer be honoured, and yet the same equipment is being used.

What does this mean for prosecutions in Scotland?

This means that as the limit is now 22 micrograms with no room for technical error, prosecutions could be brought with readings of 23 micrograms. However, before police take a breath sample at the station they must calibrate the device by simulating a breath sample. In order to deem the breathalyzer to be working correctly, the reading must fall within 3 micrograms of the permitted level. However, given that even after calibration the breathalyzer reading could be wrong by up to 3 micrograms, technically the drivers reading could be as low as 20 micrograms – below the limit for drink driving.

This is likely to lead to many cases being contested on this basis.

In a drink driving case, the breathalyzer reading is the most important source of evidence. As the court is required to have credible and reliable evidence before convicting an individual of a crime it is of utmost importance that this reading be accurate. It may also be the case that judges are reluctant to convict in marginal cases due to the danger of the driver in actuality being under the drink drive limit, and the potential to challenge the conviction.

Furthermore, given that Scotland imposes a mandatory 12 month disqualification for a drink driving conviction, the impact that a potentially incorrect conviction could have on the family life and employment of the accused seems particularly harsh if the law is unclear and the judge unsure.