THE Sunday Herald can today reveal the shocking scale of drug-driving in Scotland.

New figures reveal the same number of drivers have died on our roads after taking cannabis as those who died after drinking.

The new analysis, based on toxicology reports from driver and motorcyclists killed in road accidents across Scotland over three years, found one in five cases tested positive for alcohol consumption. The same number tested positive for cannabis - with one in five fatalities linked to the drug.

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Remarkably, despite the scale of the problem, Scotland has so far failed to introduce drug-driving limits. As part of our investigations, the Sunday Herald is today backing campaigners who want the Scottish Government to launch a crackdown and urgently follow the lead of England and Wales, which introduced legal driving limits for drugs – in a similar way to alcohol – as well as roadside ‘drugalyser’ tests two years ago.

The research is the first detailed study looking at the involvement of drugs in fatal motor vehicle collisions in nearly twenty years in Scotland.

Out of 118 cases of driver and motorcyclist fatalities examined between 2012 and 2015, a total of 24 (20%) tested positive for alcohol and 24 (20%) tested positive for cannabis.

Lead study author Dr Hilary Hamnett, a lecturer and forensic toxicologist at the University of Glasgow, said alcohol and cannabis seemed to be equally problematic.

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She said: “It is concerning. Policy makers will compare themselves to other places and say we are doing better, but there are some Scandinavian countries, for example, that have this really well under control and they have very low levels of drug use in their deceased drivers.”

The data the study was based on does not include specific details of each accident, but nearly all - 88% - of the drivers and motorcyclists were male and the ages of all victims ranged from 17 to 86. A total of 67 - 57% of the cases - tested positive for alcohol or all types of drugs not just cannabis.

The second most common type of drugs detected after cannabis were opioids - ranging from heroin to prescription painkillers such as codeine - found in 14% of cases; followed by benzodiazepines such as Valium at 12%; prescription medicines such as antidepressants at 10%; and over the counter medications at 8%. Heroin was only found in one driver.

Hamnett cautioned it was not possible to tell from the research what effect drugs or alcohol might have had on the cause of these fatal accidents, which could been influenced by factors such as the weather or actions of other drivers.

But she added: "It does give you a sense of the extent of drug use among drivers who are being killed in crashes.”

The study, published in the journal Forensic Science International, shows there was a sharp rise over the years in the number of fatalities who had taken drugs alone without any alcohol. In 2013, there were 11 such cases - or 38% of the total fatalities for that year. By 2015, there were 21 cases or 47% of the deaths.

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Hamnett said she was carrying out further research to see if there had been any impact following the cutting of the alcohol drink-driving limit in Scotland in December 2014.

She added: “Some people are always going to carry on drinking no matter what you set the limit at – but I am interested in whether some people are drinking less or are they moving onto drugs. It is an interesting question.”

Neil Greig, director of policy and research at road safety charity IAM Roadsmart, said it was an “important study”.

He said: “We don’t have the same drug driving laws as they have down south, where they have been catching thousands and thousands of drivers and it has been heralded as a great success.

“It seems odd that in England and Wales this very successful road safety legislation is working well and yet we are still waiting for the Scottish Government to make a decision.”

Across the UK, it is an offence to drive 'impaired by drugs'. In Scotland, police use the 'field impairment test' at the roadside for anyone suspected of driving under the influence of drugs, which involves a series of co-ordination tests such as walking in a straight line and standing on one leg. If the motorists fails they are taken to the police station for further tests, and prosecutors then have to prove a person's driving was "impaired" by drugs to secure a conviction.

Figures show there were 203 convictions for driving under the influence of drink or drugs in 2014-15 in Scotland - with separate figures for drug driving not available.

How England and Wales tackled drug-driving

TWO years ago in England and Wales, legislation was introduced to make it an offence to drive with certain drugs in your system – medicinal drugs are banned at certain levels and there is effectively a ‘zero-tolerance’ approach for illegal drugs.

At the same time, police forces in England and Wales were equipped with so-called ‘drugalyser’ devices, a saliva test which can be performed at the roadside to test for cannabis and cocaine.

The moves came after a major UK-wide review carried out by Sir Peter North in 2010 concluded that there was a “significant drug driving problem", which was "out of all proportion" to the 56 fatal and 207 serious injury accidents reported by police 2008 linked to impairment by drugs.

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According to figures obtained by the BBC, there were almost 8,000 arrests for drug driving in England and Wales following the first year of the new legislation.

Lucy Amos, spokeswoman for road safety charity Brake, called for “zero tolerance” on drug driving and motorcycle riding in Scotland.

She added: “Every day we see the devastating consequences of crashes caused by drug drivers and people need to understand that these substances will seriously affect their ability to drive safely."

David Stewart, Labour MSP for Highlands and Islands and a veteran road safety campaigner, said the Scottish Government had taken welcome steps cut the drink driving limit, but had been “tardy” on taking action on drug driving.

“The Scottish Government have got to look very closely at this and give Police Scotland the powers they need to be able to detect drivers who are impaired through drug misuse,” he said.

“I believe it is the hidden area of road safety and if we give the police more powers of detection we can make the roads safer across Scotland.”

A spokeswoman for the Scottish Government said: “Scotland has longstanding legislation in place that makes it an offence to drive while being impaired due to drugs.

“This continues to be used by Police Scotland, prosecutors and our courts to ensure those who take drugs and drive can be held to account for their behaviour through our criminal justice system.

“We continue to consider the practical implications of introducing drug driving limits in Scotland and will also consider any evaluation from England and Wales to help assess whether new limits here would add to the effectiveness of existing police powers tackling those who drive after taking drugs.”