Anyone who uses cannabis, even occasionally, will want to know how long it stays in their system before it’s safe to drive. What often surprises people is just how long the active compound – delta-9-tetrahydrocannabinol (THC) – can linger in the blood. Even after you feel completely sober, traces can remain for many hours, and sometimes days.
The legal limit is set very low, so it’s easy to underestimate the amount of time you need to wait before it’s safe to drive. Cannabis is now the single most common drug found in drug driving prosecutions across England and Wales.
If you would like to discuss your case, please email us at [email protected], call 0333 240 7373, or complete our online contact form.
How Long Does Cannabis Stay In Your System?
How long THC stays in your body depends on many factors:
- The strength of the cannabis.
- How it was used.
- Your size, weight, and metabolism.
There’s no reliable and precise way to predict when THC will drop below the legal limit – so the below can only be used for general guidance:
How Long After One Joint Is It Safe To Drive?
- Some studies show that in occasional users, after smoking one joint, THC can fall below the legal limit of 2 µg/L within as little as 3-6 hours. However, this period can be significantly longer when the cannabis is stronger or the person’s metabolism is slower.
- To be on the safe side, it’s best to allow at least 24 hours before driving.
How Long After Two Joints Is It Safe To Drive?
- With two joints or higher-strength cannabis, THC may stay above 2 µg/L for 12-24 hours or longer, depending on dose and frequency of use.
- Regular or heavy users can test positive for several days. THC builds up in body fat and is slowly released back into the bloodstream.
- Variations in tolerance, dosage, and body composition mean that there is no single reliable ‘safe’ timeframe – only general estimates.
‘Skunk’ v Resin in Drug Driving
Modern ‘skunk’ strains are by far the most common form of cannabis in the UK and have been grown for higher THC levels. Strength varies greatly between strains and batches, with some containing more than twice as much THC as others. In contrast, traditional resin or ‘block’ cannabis typically contains much lower THC. These differences underscore how difficult it is to predict the THC levels in a person’s body.
What is the Offence of Drug Driving in law?
Section 5A of the Road Traffic Act 1988 makes it an offence to drive, attempt to drive, or be in charge of a vehicle with a specified controlled drug in the blood above the prescribed limit.
For cannabis, the specified compound is delta-9-tetrahydrocannabinol (THC), and the prescribed limit is just 2 micrograms per litre (2 µg/L) of blood.
The offence is ‘strict liability’ – which means even if the cannabis was accidentally consumed or no longer causing any effect – a driver is guilty by virtue of simply being over the limit.
What is the Sentencing for Cannabis Drug Driving?
The guidelines show that the sentence depends heavily on whether there were any signs of impairment, such as ‘glazed eyes’ or ‘erratic driving’. As defence solicitors, we understand the importance of obtaining the case papers in the weeks before any hearing, in order to prepare fully and provide tailored advice on the likely outcome.
Possible sentencing outcomes include:
- Mandatory disqualification and a fine: At least 12 months’ disqualification, rising to a minimum of 3 years for a second offence within 10 years. A financial penalty.
- Community Orders: For example, unpaid work or a Curfew. Imposed if there is evidence of more than one substance in the body, driving a goods vehicle or obvious signs of impairment.
- Imprisonment: Where there is evidence of significant impairment or multiple aggravating features – up to 6 months in custody.
- Impact on employment and insurance: The conviction will appear on a Basic DBS certificate until it becomes spent, and on Standard or Enhanced DBS checks for at least 11 years. It can also lead to significantly increased insurance premiums and the loss of professional driving roles.
Can I keep my Licence if Prosecuted for Cannabis Drug Driving?
There are two ways to avoid a driving ban – pleading not guilty or relying on ‘special reasons’.
Drug Driving Defences / Not Guilty Pleas
Post-driving consumption of cannabis: for example, smoking a joint after getting out of the car or eating the cannabis after being pulled over by the police to avoid it being seized.
Procedural and Evidential Issues: Drug-driving cases depend on strict forensic procedures. Errors in completing forms (MGDDE or MGDD/F), informing the driver of rights, or sealing and handling samples can all undermine the evidence.
Prescription cannabis and medical use: A medical defence exists if the cannabis (THC based drug) was lawfully prescribed and taken as directed. This defence will fail if the court decides that driving was impaired.
Special Reasons
‘Special reasons’ are extenuating circumstances connected to the offence which persuade the Magistrates that it would be unfair to impose a driving ban. Examples include:
- Accidental consumption – for example, unknowingly eating a cannabis brownie.
- Passive exposure – such as breathing in second-hand smoke without realising, for instance after falling asleep at a party.
- A genuine emergency – where it was reasonable to drive in the circumstances, such as moving a vehicle to prevent danger.
Why Instruct Reeds If Charged With Driving Over The Limit For Cannabis?
We specialise in defending clients accused of drug driving and provide clear, practical advice on every stage of the process. Our team will examine every possible angle that may assist your case, including possible defence and ‘special reasons’. If a conviction can not be avoided, we aim to achieve the lowest possible sentence by outlining compelling mitigation, supported by evidence.
By obtaining the court papers early and preparing thoroughly before any hearing, we can help to reduce the understandable anxiety that comes with attending court.
We offer fixed fees so that costs are completely transparent, and we can represent you wherever you are in the country.
If you would like to discuss your case, please email us at [email protected], call 0333 240 7373, or complete our online contact form and a member of our motoring law team will get back to you promptly.
