Criminal law briefing: this month sees a new offence in Scotland of driving with drug concentrations in the body above prescribed limits – giving rise to the need for care with prescribed medication

The Drug Driving (Specified Limits) (Scotland) Regulations 2019 (SSI 2019/83) come into force on 21 October 2019. The regulations introduce a new road traffic offence regarding drug driving to Scotland. These changes have implications for all, not only for those involved in the criminal justice system.

Currently, those driving under the influence of drugs may be prosecuted under s 4 of the Road Traffic Act 1988 for “driving while impaired through drugs”, though such offences can be hard to prove.

Section 5A(1) and (2) of the Act creates an offence where a person (“D”) “(a) drives or attempts to drive... or (b) is in charge of a motor vehicle on a road or other public place, [with] in D’s body a specified controlled drug... if... the proportion of the drug in D’s blood or urine exceeds the specified limit for that drug”.

The regulations set out the 17 specified controlled drugs, including commonly occurring illegal drugs such as cocaine and cannabis and legitimately medically prescribed drugs, and the respective specified limits that apply to each drug.

Why is this offence being introduced?

The regulations will now provide consistency with England & Wales, where this offence has existed since 2015. The list of drugs and the specified limits in the regulations for Scotland are the same. The specified limits reflect a zero-tolerance approach that rules out any accidental exposure. For those medically prescribed drugs, the limits are set in line with a road safety risk-based approach at levels above the normal concentrations found with therapeutic use.

Scotland has been able to benefit from the English & Welsh earlier experience which gave an indication as to the possible scale of the problem. In the first year after the offence was introduced in England & Wales, there were nearly 8,000 arrests ( Not all of course will have resulted in successful convictions, especially since a significant number of cases were lost through problems with the Randox Testing Services. The problems comprised evidence of manipulation in the forensic testing process, but these problems should have been resolved.

Issues to be aware of 

Under s 5A(3) of the 1988 Act, it is a defence where D can show that:

  • “(a) the specified controlled drug had been prescribed or supplied to D for medical or dental purposes,
  • (b) D took the drug in accordance with any directions given by the person by whom the drug was prescribed or supplied, and with any accompanying instructions (so far as consistent with any such directions) given by the manufacturer or distributor of the drug, and
  • (c) D’s possession of the drug immediately before taking it was not unlawful under section 5(1) of the Misuse of Drugs Act 1971 (restriction of possession of controlled drugs) because of an exemption in regulations made under section 7 of that Act (authorisation of activities otherwise unlawful under foregoing provisions)”.

After the regulations come into force, one would anticipate challenges being made, using the defence when referring to medically prescribed drugs. What will be crucial will be the issue of directions from those prescribing such drugs. We are all familiar with wording on medically prescribed drugs such as “drowsiness may persist the next day and affect performance of skilled tasks such as driving”. Anyone being medically prescribed drugs could find themselves potentially liable for prosecution if they fail to comply with the relevant therapeutic limits, instructions on the packaging of the drug or advice provided from their medical practitioner.

What is required is for healthcare professionals to be aware of the commencement of the regulations and to ensure that they provide the patient with a full explanation of the medicine’s effect and its relevance to driving. Exactly how that deals with repeat prescriptions needs to be seen.

Be aware that there may be efforts to prosecute in circumstances where those driving are shown to have had a cocktail of drugs in their blood all falling under the relevant specified limits. Although prosecution cannot result for one specific drug, prosecutions could still be instructed under the s 4 offence by showing “impairment” with reference to the combined effects.

Public awareness

What is needed is for a public campaign to run in tandem with the introduction of the drug driving offence. That will ensure that the public are fully aware of the nature of the offence, implications and consequences. Advice exists on the UK Government website which may provide guidance meantime that will extend to Scotland in time.


Gillian Mawdsley, a policy executive with the Law Society of Scotland
The Author

Gillian Mawdsley, Policy team, The Law Society of Scotland

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