EducationCannabis driving laws and guidelines in the UK explained

Cannabis driving laws and guidelines in the UK explained

12 min read

Editorial Team

Cannabis driving laws in the UK


Although thorough research has been undertaken to create this blog, please note it should only be used as guidance, and does not constitute legal advice.

In the UK, it is a legal requirement to drive only when you are in a suitable condition to do so. This means being mentally alert and physically capable of controlling the vehicle at all times. There are different methods used to determine this. One of these methods involves testing for the presence of specific substances, like alcohol, THC, or other drugs, in your blood or breath.

There is no specific limit for CBD, as CBD is non-intoxicating. There is, however, a limit of 2 micrograms of Delta-9-tetrahydrocannabinol (THC) per litre of blood. THC is the main intoxicating compound produced by the cannabis sativa L. genus of plants - and also, a major component in medical cannabis. So, understandably, many patients are now questioning their rights when it comes to driving. 

Exploring the impact of cannabis on driving

In the UK, cannabis is still illegal unless it has been prescribed by a specialist doctor. On 1 November 2018, medical cannabis became a reality here in the UK, with many patients now being able to get the treatment they need through both the NHS and private clinics.

But does that mean all medical cannabis patients can drive whenever they like, as they hold a legal prescription?

No.The effects of cannabis (THC) on drivers are well documented, which we will discuss at the end of this section. 

CBD products, however, are legal providing they contain a maximum of 1mg of THC per product container. This is due to the fact that THC is the intoxicating component of cannabis.

CBD products – creams, tinctures, oils, edibles, etc. – can be found in health stores, pharmacies, and even supermarkets these days, so it comes as no surprise that many people wonder if they are legally allowed to operate a motor vehicle whilst applying or administering CBD products.

The answer, thankfully, is yes.

But this does come with a caveat. Over-the-counter CBD products have been known to (in very few cases) not contain exactly what is stated on the label. This means that you could potentially be consuming more THC than you are aware of.

In response to this, in January 2019, the UK government enacted stricter regulatory processes in the CBD industry, which should ensure that all CBD products are accurately labelled. CBD products are now classed as 'novel food items', meaning that companies must provide full lab testing results and a certificate of analysis.

Understanding cannabis' effects on driver focus and reaction

In contrast to CBD, THC is linked to a dip in cognitive function and motor skill impairments.

These impairments pose challenges for drivers in accurately perceiving the road and can have a marked impact on reaction times. THC consumption can also hinder a driver's ability to accurately assess distances, which in turn may affect their capacity to manoeuvre the vehicle correctly.

Regardless, the end result remains the same: drivers who are under the influence of THC can pose a threat not only to themselves, but also to other drivers and the wider public.

Therefore, driving while impaired by cannabis is illegal, regardless of prescription status, and is regarded in a similar light as drink-driving in the UK. 

What are the punishments for driving while impaired by THC?

If you are deemed to have been driving while impaired by THC, or have caused harm to the public, then you may also face a charge of dangerous driving. This carries significantly higher penalties, including up to 14 years in prison and an unlimited fine. If you cause the death of another person while driving while impaired by THC, then you may face a charge of causing death by careless or dangerous driving. This carries a penalty of up to life imprisonment.

Legal repercussions for THC-related driving offences

The consequences of driving while impaired by THC can also extend to your driving record, with a conviction resulting in points being added to your licence and potential disqualification from driving, which may stop you from travelling to certain overseas destinations.

The penalties that can be enforced if you are caught driving while impaired by THC include:

  • A driving ban of 12 to 36 months
  • A possible prison sentence of up to 6 months (reserved for more serious cases)
  • An unlimited fine, determined on a case-by-case basis
  • The conviction will result in a criminal record, potentially affecting foreign travel plans
  • The defendant's licence being endorsed for 11 years, which can lead to higher insurance premiums

How the cannabis limit is enforced

The cannabis driving limit is enforced in much the same way as the alcohol limit. In general, enforcement is reactionary. That is to say, the police will respond to a direct observation of concerning behaviour or to a report of it. The police will, however, sometimes conduct random stops of vehicles.

Police methods for detecting THC in drivers

The observational assessment

Police will observe the driver of the vehicle for any evidence that their driving ability is impaired. For example, they will check for signs of bloodshot eyes or for the smell of cannabis (or alcohol). This may include a specific check of how a driver’s eyes react to a stimulus, usually a moving object and/or a light.

The field impairment test (FIT)

When a police officer suspects that a driver may not be fit to operate a vehicle, they may administer one or more roadside impairment tests. Although the exact procedures can vary among different police forces and individual officers, these tests often include instructions to walk in a straight line. The purpose of these tests is to assess the driver's cognitive function, balance, coordination, and accuracy in following instructions.

The DrugWipe test

The DrugWipe test is a convenient and non-invasive method used to provide an indication of drug use. It is a highly sensitive test capable of detecting low doses of various drugs. The detection window for the DrugWipe test ranges from a few hours to a few days, depending on the specific drug and the individual's metabolism. It's important to note that a positive result from the DrugWipe test alone does not establish impairment; it just serves as an initial indicator and, hence, a justification for further testing. THC can be present in saliva or an average of 3–5 days, even after a small, single-use.

Arrest and further testing

If a police officer has reasonable suspicion of impairment, they have the authority to arrest the driver and transport them to a police station for further testing. At the police station, additional impairment tests may be conducted by a Drug Recognition Expert (DRE). Currently, the most reliable method for confirming THC-related drug impairment is through a blood sample, as there is no widely accepted and reliable urine test available for this purpose.

Knowing your limits

It's important to be aware of your limits and know that you should not drive if you are impaired by THC. Not only is it illegal, but it also poses a significant risk to yourself and others on the road. It's crucial to understand that even small amounts of THC can impair your driving abilities and lead to severe consequences, both legally and physically. 

What to do if you’re stopped by police

There are three simple rules when it comes to being stopped by the police (in any situation).

  • Rule one is to stay calm, and be polite.
  • Rule two is to do exactly what they ask you, no more and no less.
  • Rule three is to request the presence of a lawyer if you are directed to provide blood for testing purposes, or arrrested and taken to a police station for any reason. 

Knowing your rights during a police stop

If you have concerns about the legality of their actions, then you can ask them to confirm the legal basis. You should, however, be aware that the Road Traffic Act 1988 does give police the authority to conduct field impairment tests if they have reasonable suspicion of driver impairment. If you refuse to cooperate with these, the police can simply arrest you and take you to a station for testing.

If you refuse to provide a sample for testing, the legal consequences can be similar to those for a positive test result. The law does, however, recognise that some people may have legitimate reasons for being unwilling or unable to give a blood sample. For example, you might have a phobia of needles or a medical condition that makes it hard for a doctor to draw blood safely. If any of these apply to you, inform the police and request legal advice.

The Cannabis Industry Council driving guidance for medical cannabis patients

In their patient guidance, the Cannabis Industry Council summarise:

“As a patient prescribed with a cannabis medicine, you can possess and take your medicine and continue to drive a motor vehicle, so long as: 

  • You are not impaired
  • The cannabis medicine has been prescribed to you and this can be evidenced
  • You are following the directions provided by your specialist consultant and the instructions given by the manufacturer or distributor of the medicine”

The CIC explain that so long as you can provide sufficient evidence to show that you meet these three criteria, you have a statutory medical defence and should not be arrested. 

If these criteria are met, the CIC advises that you are not breaching the law by having over 2μg/L of THC in your blood, and there should be no further police action warranted. 

If, for any reason, you are arrested and taken to a police station to be interviewed under caution, it is vital to request representation from a solicitor. Inform your solicitor of your medical defence, and provide any and all information and evidence you have to prove that this is true. 

For more information about The CIC's guidance, read our full blog update here. 

UK cannabis driving laws FAQs

Is it illegal to drive under the influence of CBD in the UK?

It is not illegal to drive under the influence of CBD in the UK, as long the product used contains less than 0.2% THC and does not impair your driving abilities. However, the CBD market is subject to much less regulation than the medical cannabis market, so it's important to ensure you are using a reputable and trustworthy brand. It has been known for some consumer CBD products to have higher levels of THC than advertised, which could result in a positive drug test and potential legal consequences.

How does cannabis affect driving?

Cannabis can impair your cognitive abilities and reaction time, making it dangerous to operate a vehicle under its influence. THC, the psychoactive compound in cannabis, can affect your coordination, balance, and judgement, all of which are crucial for safe driving. It is a criminal offence to drive while impaired by cannabis, regardless of prescription status.

How long does THC stay in your system?

The length of time that THC stays in your system can vary based on factors such as frequency of use, dose, and metabolism. However, on average, THC can be detected in saliva for up to 72 hours and in blood for up to 30 days after use. It's important to note that the presence of THC in your system does not necessarily indicate impairment, but it can serve as evidence in a court case if you are charged with driving under the influence of drugs.

Can I refuse to take a drug test if I'm stopped by the police?

No, if a police officer has reasonable suspicion of impairment, they have the authority to ask you to take a roadside impairment test. Refusing to cooperate with this test can result in arrest and further testing at a police station.

Closing considerations

If you are taking medicinal THC products, it's important to be aware of the legal limits, and know when you are impaired. The guidelines above should help you understand what the legal limits are and how they're enforced - so that you can stay on the right side of the law while accessing the treatment you need.

Don't let the stigma surrounding medical cannabis prevent you from getting a suitable treatment. Releaf provides tailored monthly packages, specialist consultations for medical cannabis, and a unique medical cannabis card for protection, all based on your medical cannabis prescription.

It is important to seek medical advice before starting any new treatments. The patient advisors at Releaf are available to provide expert advice and support. Alternatively, click here to book a consultation with one of our specialist doctors.

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Editorial Team

Article written by the Releaf Editorial Team, a group of seasoned experts in cannabis healthcare, dedicated to enhancing awareness and accessibility in the field through their wealth of knowledge and experience.

Our articles are written by experts and reviewed by medical professionals or compliance specialists. Adhering to stringent sourcing guidelines, we reference peer-reviewed studies and scholarly research. View our editorial policy.

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Further reading

Insightful statistics about medical cannabis in the UK

On the 1st of November 2018, medical cannabis was legalised in the United Kingdom following advice given by the Government’s Chief Medical Advisor, Dame Sally Davies. Strict restrictions were imposed around the classification of cannabis-based products for medicinal use in humans (CBPM), as well as the prescription and dispensing of medical cannabis.

Lucy MacKinnon

Is hemp cultivation legal in the UK?

In the UK today, hemp can be legally grown for commercial purposes provided the farmer or grower receives a special licence from the home office. Growers are also only able to cultivate hemp varieties that contain lower than 0.2% THC. This is because cannabis (or more specifically, cannabis plants that contain more than 0.2%THC) is still considered a class B drug.

Sam North

The CIC takes the wheel: Medical cannabis driving guidance

The Cannabis Industry Council (CIC) has released guidance for medical cannabis patients to ensure that they act safely, and are treated appropriately, when behind the wheel. Distributed for free in physical leaflet format to attendees at The Patient Conference, which took place earlier this month during Medical Cannabis Awareness Week, this document states the rules and regulations that relate to medical cannabis patients and driving.

Lucy MacKinnon