Expert defence for DG10, DR80 and all drug driving charges — including prescription medication defences and roadside test challenges
Drug driving legislation was significantly strengthened in March 2015 with the introduction of specific legal limits for 16 controlled drugs under the Drug Driving (Specified Limits) (England and Wales) Regulations 2014. These regulations created zero-tolerance limits for illegal drugs such as cannabis, cocaine and MDMA, and medical limits for prescribed drugs including diazepam, morphine and ketamine.
The consequences of a drug driving conviction match those of drink driving: a mandatory minimum 12-month disqualification, an unlimited fine, up to 6 months' imprisonment, a criminal record, and substantial increases in insurance premiums. If you have been charged with drug driving, you need specialist legal representation without delay.
The following limits apply to illegal drugs. These are deliberately set at extremely low levels — effectively zero-tolerance thresholds designed to catch anyone who drives after taking these substances:
| Drug | Blood Limit (mcg/L) | Notes |
|---|---|---|
| Cannabis (THC) | 2 | Can be detected for weeks after use |
| Cocaine | 10 | Metabolite benzoylecgonine: 50 mcg/L |
| MDMA (Ecstasy) | 10 | Zero-tolerance |
| Heroin / Morphine | 5 (6-MAM) | See prescription limit below |
| Ketamine | 20 | Medical limit also 20 mcg/L |
| LSD | 1 | Zero-tolerance |
| Methamphetamine | 10 | Zero-tolerance |
For drugs that may be legitimately prescribed, higher limits are set — designed to allow patients to drive safely while medicated:
| Drug | Blood Limit (mcg/L) | Common Prescription Use |
|---|---|---|
| Clonazepam | 50 | Epilepsy, anxiety |
| Diazepam | 550 | Anxiety, muscle relaxant |
| Flunitrazepam | 300 | Sleep disorders |
| Lorazepam | 100 | Anxiety, insomnia |
| Methadone | 500 | Opioid dependency treatment |
| Morphine | 80 | Pain relief |
| Oxazepam | 300 | Anxiety, alcohol withdrawal |
| Temazepam | 1,000 | Insomnia |
| Code | Offence |
|---|---|
| DG10 | Driving or attempting to drive with drug level above specified limit |
| DG40 | In charge of vehicle while drug level above specified limit |
| DR80 | Driving or attempting to drive when unfit through drugs |
| DR90 | In charge of vehicle when unfit through drugs |
Under s.5A(3) of the Road Traffic Act 1988, it is a defence if a drug was prescribed or supplied to you by a medical practitioner, and you took it in accordance with the prescriber's instructions and with any accompanying manufacturer's instructions — and you were not impaired to drive. This is the primary defence for drivers charged after taking legitimate prescription medication. We gather medical evidence and expert pharmacological opinion to support this defence.
The DrugWipe 5S and Securetec devices used at the roadside are preliminary screening tools only. A positive roadside swipe does not by itself prove a drug driving offence — only a blood analysis result can form the basis of a prosecution. We scrutinise the roadside test procedure, the timing, the device approval and the officer's training.
Once you are taken to the police station, you will be asked to provide a blood sample. The sample must be divided and one half given to you for independent analysis. The chain of custody for the police's sample must be documented at every stage. Any break in continuity, contamination or improper storage of the sample can render the results unreliable. We instruct independent toxicologists to review the prosecution's analysis.
In rare cases — particularly with cannabis — a driver may have a small amount of THC in their blood as a result of passive inhalation in an enclosed space. While the zero-tolerance limit for THC is very low (2 mcg/L), in borderline cases expert evidence about the likely route of exposure can be relevant to the court's assessment.
The prosecution must prove that you were driving or attempting to drive a motor vehicle on a road or public place at the time. If there is insufficient evidence of this — for example, if you were found stationary in a vehicle — the charge may not be proved.
Cannabis is by far the most common drug found in drug driving cases. Critically, THC (the psychoactive component of cannabis) can remain detectable in the blood at levels above the legal limit for days or even weeks after consumption, long after any impairment has passed. This means that drivers who have not used cannabis recently — and who are not impaired in any way — can technically be over the legal limit. This is a genuine injustice that our solicitors address by gathering evidence of when the drug was last consumed, and where possible commissioning expert back-calculation evidence.
The Misuse of Drugs Act 1971 classification of cannabis as a Class B drug means that being found to have consumed it, even if not at the wheel, can have other legal consequences. We advise on all related implications as part of our comprehensive case management.
Get specialist legal advice immediately — before your court date.
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