Driving with cannabis in your system is against the law – even for legally prescribed patients. Read to find out more about drug tests and driving a car or riding a motorcycle as a cannabis consumer in the UK.
The Road Traffic Act 1998 states the limit for driving with cannabis in your system in the UK is zero-tolerance.
Punishment is a 12-month ban, a fine, and a potential prison sentence.
The legislation means that taking a prohibited substance and driving a vehicle will result in the police conducting a saliva swab test, arresting, and prosecuting those caught offending.
Judges will use the full force of the law when sentencing. The more in your system the harsher the sentence.
The police will arrest you and take you to the station for a full blood test if they detect one of the banned drugs.
Police can now detect traces of 8 commonly used drugs in your saliva using roadside swab test kits. The technology collects and quickly analyses saliva from the tongue and inside the mouth for one of the following substances.
| ‘Illegal’ drugs (‘accidental exposure’ – zero tolerance approach) | Threshold limit in blood |
|---|---|
| Benzoylecgonine | 50µg/L |
| Cocaine | 10µg/L |
| Delta-9-Tetrahydrocannibinol, THC (Cannabis) | 2µg/L |
| Ketamine (Esketamine) | 20µg/L |
| Lysergic Acid Diethylamide (LSD) | 1µg/L |
| Methylamphetamine | 10µg/L |
| MDMA | 10µg/L |
| 6-monoacetylmorphine (Heroin) | 5µg/L |
What is the punishment if you are caught driving with cannabis in your system?
Driving with cannabis in your system is against the law can result in the loss of your driver’s license for one or more years, along with fines of up to £5000.
The authorities may prosecute you, issue a criminal record, and potentially imprison you.
The tests detect THC in your saliva for up to 10 hours after consumption. THC takes longer to clear from the body in people who use cannabis more frequently, including legally prescribed patients,
If you use cannabis for a medical reason and do not have a legal prescription, you are at risk of arrest and losing your license under the law.
Can I drive and use cannabis as a medicine?
Patients who have a legal prescription should still proceed with driving with caution. Patients remain in a grey area because the law for driving with cannabis in your system has not been updated since medical cannabis was legalised.
Whilst there is a medical defense for driving with THC in your system as a patient, the Home Office has not yet amended the Road Traffic Act to move cannabis into the medically accepted substances.
The Home Office legalised medicinal cannabis in the UK on November 1st, 2018. Specialist doctors can legally prescribe licensed cannabis-based products for medicinal use. Doctors can prescribe patients cannabis flowers, oils, capsules, vape pens, and lozenges.
If the police think you’re impaired and a danger on the road, they need to show evidence to support their belief.
Read the advice from the Cannabis Industry Council on Cannabis and driving with a prescription.
What levels of prescribed drugs can I have in my system when driving?
The Home Office has imposed limits on the acceptable amount of other listed medications frequently used without a doctor’s prescription in the blood.
When you have been taking medication for some time, you become used to any side effects that may impair your judgment due to tolerance.
The law on cannabis makes it a legal medicine and it should be moved to this table from the previous to give patients the right to drive with their prescribed medicine in their system.
| ‘Medicinal’ drugs (risk-based approach) | Threshold limit in blood |
|---|---|
| Amphetamine | 250µg/L |
| Clonazepam | 50µg/L |
| Diazepam | 550µg/L |
| Flunitrazepam | 300µg/L |
| Lorazepam | 100µg/L |
| Methadone | 500µg/L |
| Morphine | 80µg/L |
| Oxazepam | 300µg/L |
| Temazepam | 1,000µg/L |
Here is a playlist of videos that we have compiled to inform you more about the drug-driving laws.
Below is more information, FAQ, and advice that we think you should make yourselves aware of.
What is drug driving?
Drug driving is when someone is in charge of a motor vehicle when they are under the influence of drugs. It is illegal, under the Road Traffic Act 1998 to operate or be in control of, a car or motorbike on a road or in a public place with a certain amount of drink or drugs in your system or unfit to drive.
Is the cannabis driving law legal?
Yes, the government can introduce zero-tolerance drug driving limits. One of the main supporting arguments is that it is against the law to possess these drugs in the first place, why would it be OK to drive while on them? The law gives police the power to arrest people who may not be a danger to the public but have a banned substance in their system. Dealing with the issue in this manner is not scientific and lacks evidence-based support.
What if I am driving with cannabis in my system, and test positive, but I am not impaired?
Regrettably, just being unimpaired won’t be enough to prevent the police from securing a prosecution against you. Driving with any cannabis in your system is against the law. The swab test first to determine if it is a contributing factor. The police have roadside sobriety and cognition tests, which many experts agree show if someone is competent to operate a car or not.
What happens if my cannabis swab test is positive?
If your test results show a positive presence of THC, you will face arrest under the Road Traffic Act 1988. Following that, authorities will transport you to a police station or hospital for a blood test to ascertain the precise levels of THC in your blood. The higher the level over the limit, the harsher the sentence will be when it goes to court.
What if my cannabis swab test is negative?
Your cannabis swab test may come back negative, but the police may still have reason to believe you are impaired with a drug they do not test for. They may ask you to carry out a roadside impairment test. These tests will assess your cognitive ability to see your level of competence. The test will include a one-leg stand, a pupillary examination, a walk-and-turn test, and a modified Romberg balance test.
How long does cannabis stay in your system?
Cannabis stays in your system for different amounts of time depending on how you consumed it, how much you took, your body type, and your weight. The psychoactive effects of smoking and vaping cannabis last for three to six hours, but the inactive metabolites (the things THC breaks down to when your body has processed it) can stay in your body for up to a month. Eating THC products (cannabis edibles or tinctures containing THC) can last for four to 12 hours. The higher the dose, the longer the effects can last.
The body stores inactive cannabinoid metabolites in the fat and releases them slowly over a month to six weeks. This can result in blood tests showing the metabolite 11-hydroxy-THC. The more a person uses, the longer it takes to be completely free of any cannabinoid metabolites. This means that urine tests can show 11-hydroxy-THC even if the person hasn’t smoked or eaten any THC or cannabis for a month.
The driving law for cannabis has the lowest detectable limit for any drug.
When can the police test me for cannabis when driving?
The police can stop you when driving and ask you to complete a road safety test if they have reasonable grounds to believe you are driving whilst intoxicated. This could be erratic and dangerous driving, or they have seen drugs or drug use in your car.
You will be asked to complete a roadside drug test if you are involved in a traffic accident and suspect one of the drivers of being under the influence of a banned substance or alcohol.
The best way to avoid being asked to complete a roadside saliva swab is to not drive around with a car smelling of cannabis. Whilst the smell of cannabis alone is not an indicating factor that cannabis will be found, it can still be used as evidence in circumstances when you are driving or operating a heavy vehicle.
What happens if I fail to give the police a roadside saliva swab for cannabis?
If you fail to give a saliva test for cannabis when the police pull you over and ask you, they will place you under arrest for failing to provide a sample. They will take you to the nearest police station that can take your blood to be tested. If you are found to have THC in your blood, you will be arrested again on further charges of drug driving. The judge will take note of this when sentencing and see it as an aggravating factor.
What happens if I fail or am unable to give a blood sample to the police?
The police must have permission from you to collect a sample. If you fail to give a blood specimen to the police, you will be charged with a separate offence (Section 7). The starting sentence is 12 months of custody.
Having a needle phobia must have prior recognition from a medical professional for it to be considered a reason to refuse and may be used as mitigation in your trial.
What is the sentence for drug driving with cannabis?
The sentence for drug driving with cannabis in your system is a minimum of a 12-month driving ban and a fine. The fine is down to the court and your income may play a factor in the total arrived at, but it may be unlimited. The court can give a community service order, up to six months in prison, and a longer-lasting driving ban.
If you cause risk to life or kill someone whilst driving under the influence of cannabis, you can face prison time of up to 14 years.
Drug driving is a criminal offence, and no matter how small you think the charge is, you will receive a criminal record for the charges.
How long do the police have to charge you for drug driving if they get a positive test result?
If you provide a positive test result for driving with cannabis in your system, the police have six months to file charges against you.
Under what circumstances can I avoid a cannabis driving ban, if it is found in my system?
Advice to stay safe driving as a cannabis consumer
- Don’t smoke and drive
- Do not drive if you feel impaired, even if it’s been a while after consuming.
- Choose a designated driver who stays sober
- Use mouthwash after you smoke and before you drive
- If you carry cannabis in your bag, use an airtight jar or container to conceal the smell
- Have a clean car; do not have any cannabis or smoking paraphernalia visible
Here is Fifth Gears test on cannabis and driving.
If you have been stopped and tested for drugs under the new system, please get in touch and let us know what happened in the comments below. If you have any questions about the new driving laws and limits, please ask in the comments and we will add them to the blog.
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