With cannabis use on the rise and its legality in flux in many countries, including the UK, many users likely wonder, “How long after smoking weed can you drive?” Whether you are a recreational marijuana user or have a prescription for medical cannabis, it’s more important than ever to understand how a drug will affect your body when you get behind the wheel, how much is safe to use before driving, and how long after use you should wait before hitting the road.
In this article, we’ll unpack some of the UK’s drug driving laws regarding marijuana to help you make informed decisions, understand the legal limit, the consequences of getting caught driving under the influence, and how you can avoid ending up on the wrong side of the law.
What is Considered Drug Driving?
Prosecuting drivers for drug driving is less straightforward than drink driving. While there is a firm limit for blood alcohol concentration, which is easily determined with a breath, blood, or urine test, determining the concentration of a drug in someone’s system is more complex. In 2015, the Road Traffic Act 1988 amended its provision of drink and drug driving offences, making it an offence in England and Wales to drive with certain illegal drugs and prescription medications above specified limits in your body.
Cannabis has the lowest threshold of the drugs on this list, at just 2 micrograms per litre of blood. For context, a single puff on a joint can put you over this threshold, and police use a zero-tolerance policy for prosecuting drivers who are over the legal blood level. An average joint will cause a typical peak THC concentration of 84.3 – 162 micrograms, but the blood level drops rapidly a few hours after use. Cannabis is a Class B illegal substance in the UK, known to impair driving performance by impacting motor skills and reaction times and causing impaired judgement.
How is the Legal Limit Measured?
Cannabis impairment is measured by the presence of two key THC metabolites in your system, Delta-9-THC and Delta-9-Carboxy-THC. When you get pulled over for suspected driving under the influence of drugs, police will usually test how much cannabis is in your system using a saliva sample test kit called a drugalyser. If this roadside test shows you are over the legal limits, you will likely be taken to a police station, where a urine or blood test will be administered.
After you consume cannabis, it can remain in the system for days or even weeks, but THC levels typically peak within 10 minutes after smoking weed and can significantly decrease within three hours. Oral fluid tests like the ones used by police can detect cannabis use within the last four to six hours.
It is important to note that the legal limit is not a green light to drive after you smoke cannabis, but only a marker for when cannabis’s effects on driving can be deemed impairing. How quickly you metabolise cannabis will depend on several factors including physical characteristics like weight, age, and gender, as well as variables like how much you have eaten or medications you have taken. Smoking cannabis affects everyone differently, and it is difficult to predict how your driving skills will be impacted, how much will put you over the limit or for how long.
Can Police Drug Test You For No Reason?
Police can only drug test you if they have reasonable suspicion that you are under the influence of drugs. However, if you commit a traffic violation or are involved in a traffic accident, the police can choose to drug test you without reasonable suspicion.
Drivers who refuse a roadside drug test passively admit guilt and will be arrested. If you are taken to a police station, different methods to test for THC, like a urine or blood test will be done and, if positive, can carry penalties similar to those for breathalyser tests.
How Long After Smoking Weed Is it Safe to Drive?
For occasional cannabis users, the general advice is to wait at least four hours to drive after smoking to ensure THC levels are within the legal limit. However, as with all drugs, abstaining from smoking cannabis before driving is the only foolproof way to reliably prevent impairment and consequences. As mentioned above, several factors control how long THC stays in your system, some of which can vary day-to-day. This makes it difficult to guess when it might be safe to get back behind the wheel.
What are the Penalties for Driving After Smoking Cannabis?
Those caught driving under the influence after smoking cannabis face harsh penalties that can include:
- Automatic driving licence disqualification for at least 12 months. This will increase significantly to three years upon subsequent offences.
- A criminal record that will show up on DBS checks for 11 years. These checks are used by employers, landlords, and border security in certain countries, impacting many aspects of the convicted person’s life.
- An unlimited fine, at the court’s discretion.
- Up to six months in prison, in extreme cases.
- Insurers may raise car insurance costs or even refuse to cover the driver post-conviction.
- If your careless driving after smoking weed causes a death, you may face an upper limit of a 14-year prison sentence.
Driving a motor vehicle after consuming cannabis carries significant risks for both the driver and others on the road. Because it is harder to gauge how much THC you consume than easily-measured substances like alcohol, and because weed is still considered an illegal drug for most users, which carries its own set of laws and punishments, users should take great care to avoid prosecution.
Medical Marijuana vs Recreational Cannabis
Despite cannabis’s gradual acceptance in society, UK law takes a stringent approach to drug enforcement, especially when you’re behind the wheel. In 2018, the UK made cannabis legal for medical use, and when lawfully obtained it is treated like other prescription medicines in the eyes of the law. Marijuana is illegal for recreational use, but you can still be prosecuted if you are prescribed medical cannabis and drive after smoking more than the dosage recommended by your healthcare professional.
How Can a Solicitor Help?
If you are charged with driving under the influence of marijuana, a solicitor like the experts at #1 Motoring Solicitors can be an invaluable resource for navigating the legal process and attempting to avoid a drug-driving conviction. One of the first things they will do is to advise you to refrain from giving any self-incriminating statements to law enforcement. It is critical to avoid admitting to any guilt until there is a solicitor there to represent you. They will then meticulously review the circumstances surrounding the arrest, including whether you were subject to passive smoking and whether roadside testing was valid to determine if the proper protocols were followed, and how any samples were handled.
Solicitors will look for potential defences based on your medical history or other such factors that could have made test results inconclusive. They can gather evidence like medical records or the testimony of an expert to argue that the mere presence of marijuana in a person’s system did not necessarily mean the substance impaired their ability to safely operate a vehicle at the time of the arrest. Solicitors can also speak with prosecutors to pursue alternative resolution, like rehabilitation programs or lesser charges altogether, depending on the circumstances of the case and the defendant’s criminal history. By fighting for their client’s rights and examining every legal option that may be available, a solicitor can help a person who has been charged with drug driving in the UK to minimise the potential fallout and protect their interests.
Final Thoughts: Avoiding Prosecution
The key takeaway to preventing prosecution for drug driving is to avoid it in the first place. If you plan to smoke cannabis, be aware of the guidelines for how long it can take THC to leave your system. If in doubt, arrange alternative transportation, like a designated driver, taxi, rideshare, or public transportation. While the guidelines for THC are less straightforward than alcohol and other drugs, caution and common sense are your allies. Keep in mind that just because you no longer feel impaired after smoking cannabis doesn’t mean the THC in your system doesn’t exceed the limit.
By understanding the potential repercussions and preparing ahead of time, you can avoid a situation where you might face prosecution for driving under the influence of cannabis. If you do find yourself in this situation, enlisting help from an expert, like #1 Motoring Solicitors, can help prevent a driving ban and protect your rights.