New drivers learn the drink-drive limit early, but drug-driving law is less consistent across the UK, and a new driver moving between nations, or simply learning in one and driving in another, needs to know that the rules are not the same everywhere.
England and Wales: a specified-limits offence
Section 5A of the Road Traffic Act 1988 created a specific offence of driving, attempting to drive, or being in charge of a motor vehicle with a specified controlled drug in the body above a set limit, regardless of whether the driving itself was actually impaired. The Drug Driving (Specified Limits) (England and Wales) Regulations 2014 set the actual limits, listing 18 controlled substances at the time they came into force on 2 March 2015, with a threshold expressed as a concentration in blood for each one; cocaine, for example, is set at 10 microgrammes per litre of blood, Delta-9-Tetrahydrocannabinol (the active component of cannabis) at 2 microgrammes per litre, and morphine at 80 microgrammes per litre. Amphetamine was added by amendment at a limit of 250 microgrammes per litre, effective from 14 April 2015. Because this is a specified-limits offence rather than an impairment offence, the prosecution does not need to show the drug affected the driver’s ability to drive, only that the limit was exceeded.
Scotland: its own separate regulations
Scotland runs a separate instrument, the Drug Driving (Specified Limits) (Scotland) Regulations 2019, which came into force on 21 October 2019 and, like the England and Wales regulations, creates a strict-liability offence under section 5A of the 1988 Act rather than requiring proof of impairment. Scotland’s regulations cover 18 controlled drugs, with example limits including cocaine at 10 microgrammes per litre of blood, Delta-9-Tetrahydrocannabinol at 2 microgrammes per litre, MDMA at 10 microgrammes per litre, and Lysergic Acid Diethylamide (LSD) at 1 microgramme per litre, the lowest limit on the Scottish list. Several of these figures line up closely with the England and Wales limits for the same drugs, but because the two regimes come from separate statutory instruments, they are not guaranteed to move together if either nation amends its list in future. Scotland’s separate impairment-based offence, for driving while actually affected by drugs, continues to operate alongside the specified-limits offence rather than being replaced by it.
Northern Ireland: no specified limits at all
Northern Ireland does not have an equivalent specified-limits regime. Official government guidance is direct on this point: the specified-limits law “does not cover Northern Ireland,” though a driver can still be arrested there if unfit to drive through drugs. This means Northern Ireland relies on an impairment-based offence, where the prosecution has to show the driver’s ability was actually affected, rather than the strict-liability, limit-based approach used in England, Wales and Scotland. A new driver who learned and tested in Great Britain should not assume the specified-limits framework, or its underlying logic that a limit alone is enough for a conviction, applies in the same way once driving in Northern Ireland.
What this means for a new driver
Because the England and Wales and Scotland regimes are both strict-liability, a driver in either nation can be convicted for exceeding a specified limit even where their driving showed no visible sign of impairment, which makes the legal position considerably less forgiving than many new drivers assume. Prescribed medication is a relevant complication in both regimes: driving with certain drugs above the specified limit is not an offence where the driver has been prescribed the medication and taken it in line with that advice, but this defence depends on being able to show the prescription, not simply on holding one in principle.
Common questions
Can I be convicted for a legal, over-the-counter medicine? The specified-limits offences in England, Wales and Scotland are built around controlled drugs, both illegal drugs and certain prescription-only medicines at levels beyond normal therapeutic use, rather than ordinary over-the-counter products, though driving while impaired by any medicine remains a separate risk regardless of which specific offence might apply.
Does passing my driving test in England mean I know the drug-driving rules for Wales too? Yes, in the sense that the Drug Driving (Specified Limits) (England and Wales) Regulations 2014 apply to both nations under the same instrument, so the limits themselves do not change at the Wales border.
If I am prosecuted in Northern Ireland, does the prosecution have to test my blood against a specific number? No. Because Northern Ireland uses an impairment-based offence rather than the specified-limits approach, the prosecution has to establish that the driver was actually unfit to drive, rather than simply that a blood test exceeded a defined threshold.
The bottom line
England and Wales and Scotland both operate strict-liability, specified-limits drug-driving offences under section 5A of the Road Traffic Act 1988, each set out in its own separate regulations, the 2014 Regulations for England and Wales and the 2019 Regulations for Scotland, with broadly similar limits for drugs such as cocaine and cannabis but no guarantee the two lists stay aligned if either nation updates its own regulations. Northern Ireland has no specified-limits offence at all, relying instead on an impairment-based approach where actual unfitness to drive has to be shown. A new driver learning the rules in one nation should treat drug-driving law as genuinely different in Northern Ireland rather than assume it mirrors the rest of the UK.
Sources
- GOV.UK, “Drugs and driving: the law”
- legislation.gov.uk, “The Drug Driving (Specified Limits) (England and Wales) Regulations 2014, Regulation 2”
- legislation.gov.uk, “The Drug Driving (Specified Limits) (Scotland) Regulations 2019”