How Long After Smoking Weed Can I Drive?

Although there have been calls to make cannabis legal in the UK, it’s still classified as a class B drug and is therefore subject to strict drug driving laws. Ultimately, the use of illegal substances, controlled drugs and certain prescription medicines before driving represents a significant public health issue.

CBD and THC are two of the most prominent cannabinoids found in the cannabis plant. Whilst CBD is legal and commonly found in oils, skincare products and gummies, THC is illegal in the UK. If you’re caught with THC in your system while driving, you could face harsh penalties and even a prison sentence.

So, how can you ensure that you don’t fail a roadside field impairment test or cannabis blood test? Keep reading to discover how long you need to wait after smoking weed before driving.

Weed Law in the UK

The UK has adopted a zero-tolerance approach towards drug driving involving illegal drugs, including cannabis. With alcohol, you’re allowed a certain amount in your system without being guilty of drunk driving, but if any amount of illegal drugs can be detected in your system by a roadside test or blood test, this can lead to you being prosecuted for dangerous driving through drug use.

Therefore, if you smoke cannabis, you’ll be breaking the law if you start driving under the influence, even if you only consumed a small amount. Additionally, if you consume a larger amount, this could remain in your system for a long time, so you can’t get behind the wheel for many hours.

Overall, even if you feel fine having cannabis in your system can cause impaired judgement, slower reaction times and decreased concentration, increasing your risk of causing road accidents.

Weed Legal Limit

However, to rule out accidental exposure to an illegal drug like cannabis, there are legal limits set for each type of drug. For cannabis, this legal limit is set at just 2 micrograms of THC per litre of blood. If you’re over this limit, even by a small amount, you’ll face prosecution.

One exception to this rule is the use of medical cannabis, which became legal in 2018. Smoking cannabis for medical reasons could help you avoid drug driving penalties, although you’ll need to prove that it was lawfully obtained, had been supplied for medical or dental purposes and that it was taken in accordance with the directions issued at the time.

How Long Should I Wait?

Unfortunately, there’s no hard and fast rule for how long you should wait before driving after recreational cannabis use. This is because cannabis is not regulated, so you can’t know for sure how much THC you’re consuming.

Generally, an average-sized joint should contain around 120 micrograms of THC, although weed has been becoming more potent over the last few years. The half-life of the THC metabolites will determine how long you need to wait – this is the amount of time it takes for the THC in your bloodstream to reduce by half.

Again, this isn’t a foolproof calculation as the half-life will be affected by the amount of THC you take and also your physical characteristics, such as your height and weight. Waiting at least 12 hours should be enough if you’ve consumed around 120 micrograms of THC, but it’s best to wait at least 24 hours if you want to be safe.

Drug Driving Penalties

So, what happens if you’re caught driving while high or driving while smoking weed?

The police may stop you because they have a reason to suspect that you’re on drugs. For example, they could witness erratic or dangerous driving. Or, they may pull you over for another reason and then start to suspect you’re on drugs once they talk to you.

After the police have pulled you over and confirmed that they suspect you’re driving under the influence of drugs, they will require a roadside saliva swab using a home office approved kit.

If the result of this test is positive you’ll be taken to the police station to provide a specimen of blood. If the specimen is found to contain the drug at a level higher than the prescribed limit you will be prosecuted.

Following a drug driving conviction, you can expect to face penalties such as a minimum 1 year driving ban (3 years if you have a previous disqualification for drink or drug driving within the last 10 years) together with a fine of between 100 to 150 % of your net weekly income. Once you can drive again, you’ll also find that your car insurance costs will increase significantly.

What to Do If You’re Caught

If you’re charged with drug driving due to cannabis consumption, then you’ll need to speak to a specialist drug driving solicitor as soon as possible. They can advise you of any defences which may apply, such as passive smoking, taking cannabis-based medicines and procedural errors during the cannabis blood test.

Contact Drug Driving Solicitors today if you’re facing a drug driving charge. We’ve secured hundreds of acquittals for motoring offences, so you can be sure you’re in good hands.