Drug driving is taken as seriously as drink driving under UK law — in some respects more so, given that for many controlled drugs there is effectively a zero-tolerance limit. Whether the substance involved is illegal or a legally prescribed medication, being found with drug levels above the specified limit while driving can result in a mandatory driving ban, a criminal record, and in the most serious cases a prison sentence.
Our solicitors in Bolton represent clients facing drug driving charges and can advise on the evidence against you, available defences, and the realistic outcome of your case from the outset.
What Is Drug Driving?
Drug driving is the offence of driving or attempting to drive a motor vehicle on a road or public place while over the specified limit for a controlled drug, or while unfit to drive through drugs. It is governed by section 5A of the Road Traffic Act 1988, which was introduced in 2015 and established specific legal limits for both illegal and prescribed drugs.
It is important to understand that there are two distinct ways a drug driving charge can arise:
Driving over the specified limit — where a blood test reveals that a controlled drug is present in your system at or above the specified threshold. This is a strict liability offence — it does not matter whether your driving was actually impaired or whether you knew the drug was in your system. If the limit is exceeded, the offence is committed.
Driving whilst unfit through drugs — this is the older offence under section 4 of the Road Traffic Act 1988, which predates the 2015 changes. It does not rely on a specific blood limit but requires the prosecution to prove that your driving was actually impaired by drugs. This charge is less common since the introduction of specified limits but is still used, particularly where the substance involved does not have a specified limit.
What Are the Legal Limits for Drug Driving?
The specified limits for drug driving in England and Wales are set out in the Drug Driving (Specified Limits) (England and Wales) Regulations 2014. They cover both illegal drugs and some prescribed medications.
Illegal Drugs — Zero Tolerance Limits
For illegal drugs, the specified limits are set at a very low level — effectively zero tolerance, designed only to exclude accidental contamination:
| Drug | Limit in blood (micrograms per litre) |
|---|---|
| Cannabis (THC) | 2 µg/L |
| Cocaine | 10 µg/L |
| Ecstasy (MDMA) | 10 µg/L |
| Heroin / Morphine | 5 µg/L |
| Ketamine | 20 µg/L |
| LSD | 1 µg/L |
| Methamphetamine | 10 µg/L |
| 6-Monoacetylmorphine (6-MAM) | 5 µg/L |
These limits are deliberately low. A person who used cannabis the previous evening and whose driving is entirely unimpaired can still be over the limit the following morning. Cannabis in particular can remain detectable in blood for 12–24 hours after use.
Prescribed Drugs — Medical Defence Limits
For medications that have a legitimate medical use, higher limits apply — set at a level designed to capture impaired driving rather than the use of properly prescribed medication:
| Drug | Limit in blood (micrograms per litre) |
|---|---|
| Amphetamine | 250 µg/L |
| Clonazepam | 50 µg/L |
| Diazepam | 550 µg/L |
| Flunitrazepam | 300 µg/L |
| Lorazepam | 100 µg/L |
| Methadone | 500 µg/L |
| Morphine | 80 µg/L |
| Oxazepam | 300 µg/L |
| Temazepam | 1,000 µg/L |
Where a driver is over the limit for a prescribed drug but has a valid prescription and has been taking the medication in accordance with their doctor’s advice, the statutory medical defence may be available — see below.
How Do the Police Test for Drug Driving?
Stage 1 — Roadside Screening Test
If a police officer suspects you have taken drugs — through your behaviour, the smell of cannabis, or any other indicator — they can require you to take a roadside drug test. The most commonly used device is the Dräger DrugTest 5000, which tests a saliva swab for the presence of cannabis and cocaine.
If the roadside test is positive — or if the officer has other grounds to believe you are impaired by drugs — you will be arrested and taken to a police station for further testing.
Stage 2 — Blood Test at the Police Station
At the police station, a doctor or registered healthcare professional will take a blood sample. This is divided into two parts — one retained by the police for analysis, and one provided to you so you can arrange independent analysis if you wish.
The blood sample is sent to a forensic laboratory for analysis. The results will show the concentration of any drugs present in your blood. If the concentration exceeds the specified limit for any drug, you will be charged with the section 5A offence.
Refusing to Provide a Sample
Refusing to provide a blood sample without a reasonable excuse is a separate offence under the Road Traffic Act 1988 and carries the same penalties as drug driving itself. You should always seek legal advice from our police station representation team before making any decision about whether to provide a sample.
What Are the Penalties for Drug Driving?
A drug driving conviction carries the following penalties:
- Mandatory driving ban of at least 12 months — this is the minimum and cannot be avoided except in very exceptional circumstances
- Up to 6 months in prison
- An unlimited fine
- A criminal record
- A note on your driving licence for 11 years
Where the offence is aggravated — for example where the driver caused an accident, was significantly impaired, was carrying passengers (particularly children), or had a previous drug driving conviction — the penalties are significantly higher. A second conviction within 10 years carries a minimum 3-year ban.
Drug driving that results in the death of another person is charged as causing death by dangerous driving or causing death by careless driving while under the influence, both of which carry a maximum sentence of life imprisonment.
Is There a Medical Defence?
Yes. For prescribed drugs — those with the higher limits set out above — a statutory medical defence exists under section 5A(3) of the Road Traffic Act 1988. The defence applies where:
- The drug was prescribed or supplied to you by a medical practitioner
- You took the drug in accordance with the instructions given
- Your driving was not impaired by the drug
All three elements must be satisfied. The defence does not apply to illegal drugs, and it does not apply to prescribed drugs taken in larger quantities than directed or combined with other substances in a way that causes impairment. If you are taking prescribed medication and are concerned about drug driving, seek medical advice about whether it is safe for you to drive before getting behind the wheel.
Can a Drug Driving Charge Be Challenged?
Yes — in some cases. Potential grounds for challenge include:
Procedural errors in the testing process — the roadside device must be properly calibrated and used in accordance with the manufacturer’s instructions. The blood sample must be taken by an authorised person and the chain of custody maintained correctly. Any failures in this process may affect the admissibility of the evidence.
Challenges to the laboratory analysis — the blood sample retained by you can be independently analysed by a laboratory of your choice. If the independent result differs significantly from the police’s result, this can be used to challenge the prosecution’s evidence.
Medical defence — as described above, for prescribed drugs taken in accordance with medical advice where driving was not impaired.
Necessity — in very rare circumstances, a necessity defence may apply where you drove in genuine emergency circumstances with no alternative.
Our drug driving solicitors will review the evidence in your case and advise honestly on whether any defence is available and the realistic prospects of success.
Impact of a Drug Driving Conviction Beyond the Ban
Beyond the driving ban and criminal record, a drug driving conviction can have significant wider consequences:
- Insurance — premiums will increase substantially for a minimum of 5 years and some insurers may refuse cover entirely
- Employment — any job requiring a clean driving licence or a criminal record check will be affected
- Travel — entry to the United States, Canada, and other countries may be restricted
- Professional registration — those in healthcare, legal, or other regulated professions may face disciplinary proceedings
If losing your licence would cause you or your family exceptional hardship — for example by costing you your job — it may be worth discussing an exceptional hardship application with your solicitor, though this is more typically available in totting up cases than mandatory ban cases.
How Hi Solicitors Can Help
Whether you have been charged with drug driving involving an illegal substance or a prescribed medication, our driving offence solicitors in Bolton can advise you on the evidence, any available defences, and the realistic outcome of your case. We attend police stations 24 hours a day, 7 days a week, and represent clients at the Magistrates Court and Crown Court.
Call 01204 371 414 for a free initial consultation. We are here to help.
187b Derby St, Bolton, BL3 6JT · hisolicitors.co.uk
Frequently Asked Questions
Q: Can you be charged with drug driving the day after taking drugs?
Yes. The specified limits apply regardless of when the drug was taken and regardless of whether your driving is actually impaired. Cannabis in particular can remain in the blood at levels above the specified limit for 12–24 hours after use, meaning a driver who used cannabis the previous evening could still be over the limit the following morning.
Q: What is the difference between drug driving and drink driving?
Both are driving offences involving substances that affect fitness to drive, but they operate under different legal frameworks. Drink driving uses a breath test as the primary evidential tool. Drug driving uses a blood test. The legal limits and the testing procedure differ significantly. Both carry a mandatory minimum 12-month ban and can result in imprisonment. For more detail on drink driving, see our guide: Drink Driving in the UK: Limits, Penalties and What to Do If Charged.
Q: Can prescribed medication cause a positive drug driving test?
Yes. Several commonly prescribed medications — including diazepam, morphine, and methadone — have specified limits under drug driving law. Taking prescribed medication above the specified limit can result in a positive blood test. However, a statutory medical defence exists for prescribed drugs taken in accordance with medical advice where driving was not impaired. If you are taking prescribed medication, always check with your doctor whether it is safe to drive.
Q: What happens if I refuse a roadside drug test?
Refusing a roadside saliva screening test without reasonable excuse is a criminal offence. Refusing to provide a blood sample at the police station is similarly an offence carrying the same maximum penalties as drug driving itself. You should always take legal advice before deciding how to respond to a request for a sample.
Q: Does a drug driving conviction stay on my licence?
Yes. A drug driving conviction is recorded on your driving licence and remains there for 11 years from the date of conviction. During this period it must be disclosed to insurers and on relevant applications. An endorsement code DR80 (drug driving) or DR10 (drink driving) will appear on your licence.
