10 Common Myths About Drug Driving Charges in the UK

November 10, 2023 10:11 am
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10 common myths about drug driving charges

Drug driving is a growing problem on roads across England and Wales. Recent statistics show that drug driving offences have risen sharply, with many drivers unaware of the stringent laws and severe penalties around driving while over specified drug limits.

However, there are also many myths and misconceptions around drug driving charges that need to be debunked. Even experienced drivers can be confused about exactly what constitutes drug driving, how police test for it, what the penalties entail, and how taking prescription or over-the-counter medications can result in a conviction.

To help drivers stay safe and within the law, this blog post will examine and clarify the top 10 most common myths about drug driving charges in England and Wales. We’ll provide the facts around testing procedures, legal drug limits for different substances, defences that don’t hold up in court, and the consequences for first time and repeat offences of drug driving.

Debunking these drug driving myths can help save drivers from making wrong assumptions or risky decisions that could end up costing them their licenses and livelihood. By learning the truth on these 10 common misconceptions, drivers can avoid easily preventable offences and feel confident they fully understand England and Wales’ drug driving laws before getting behind the wheel.


Myth #1: You won’t get convicted if you swerve to avoid an accident.

Fact: Swerving in itself is not a defence against drug driving charges. The cause of the swerving is irrelevant – what matters is if you exceeded the drug limits in your system.

For example, you may swerve sharply to avoid a child running into the road. But if tested over the legal limits for cocaine or cannabis, you can still be convicted for drug driving even though the swerving was to prevent an accident.

The law does not allow exceptions for erratic driving needed to avert danger. Prosecutors just need to prove you broke the drug thresholds while operating a motor vehicle. Driving behaviours leading up to testing is not taken into consideration, even if you had valid safety reasons.

So don’t presume that swerving for safety means you can avoid drug driving penalties. The circumstances behind the driving itself are legally irrelevant if you test over the limits.


Myth #2: Police need a warrant to perform a drug test on you.

Fact: Police do not need a warrant to administer roadside drug testing if they reasonably suspect you of drug driving. Under the drug driving law, police have the power to stop drivers and administer “preliminary impairment test” as well as roadside drug screenings without needing to obtain a warrant first.

If police see signs of impairment such as slurred speech or lack of coordination, they have grounds that require you to take part in preliminary impairment tests. If you fail these assessments, or if officers have reasonable suspicion of drug use, they can require a roadside drug screen without a warrant. Refusing to cooperate can lead to arrest.

Additionally, after a positive roadside drug test, police can use their powers to require a blood sample for laboratory analysis without needing to get a warrant first. While police do need warrants in many cases, drug driving investigations are an exception if they already have cause for suspicion. So don’t count on police needing a warrant before testing you – they have the right to administer roadside drug tests if you appear impaired.


Myth #3: The penalties are minor for a first offence.

Fact: This is completely false. The penalties for drug driving convictions are severe even for first time offenders in England and Wales. A first offence will result in a minimum 1 year driving ban and an unlimited fine. You may also face up to 6 months in prison.

Your driving licence will also show you have a drug driving conviction for 11 years. This can make it challenging to find employment that involves driving. The court can also order you to complete a drug rehabilitation program.

With such stiff penalties on the line even for first time offences, it’s important not to underestimate the consequences of drug driving no matter how experienced of a driver you are. The laws and limits are designed to be strict for all offenders, not just repeat offenders. So don’t assume you’ll just get a slap on the wrist for a first time drug driving charge – the convictions have life-altering penalties.


Myth #4: Drug driving limits don’t apply to you if you have a high tolerance.

Fact: This is false. The legal drug limits set by the drug driving law apply equally to all drivers regardless of individual tolerance levels. Even if you have built up a tolerance and don’t feel impaired after taking a drug, you can still be convicted if a blood test shows you exceeded the specified limits.

For example, an experienced cannabis user with a high tolerance may not feel impaired at levels of THC that would intoxicate occasional users. However, if they are tested and found to be over the 2μg/L THC limit, they are still guilty of drug driving under the law.

Likewise with cocaine, heroin, ketamine and other drugs – even if you are a habitual user with a high tolerance, the legal limits remain the same for all motorists. Tolerance does not exempt you from being prosecuted if you exceed those drug thresholds while operating a vehicle. So never assume you can’t be charged simply because a drug amount doesn’t impair your own driving ability.


Myth #5: You can argue your driving was not impaired.

Fact: The drug driving law does not actually require the prosecution to prove your driving was impaired. The key factor is simply whether you exceeded the specified limits for a drug while operating a vehicle.

Therefore, even if you manage to drive normally without any signs of impairment, you can still be convicted if a blood test confirms you were over the legal limit for a prohibited substance. For example, you may be an experienced amphetamine user who doesn’t swerve or have slow reactions after taking it. But if tested over the legal amphetamine limit, you would still face conviction and penalties.

The law does not bother with arguments over whether certain drug levels actually impaired your driving ability. All that matters is if you broke the established limits while driving. So it is never a defence to say the drugs did not impair your road performance, or that you seemed to drive safely. The limits apply equally to all.


Myth #6: Eating poppy seeds can cause a positive drug test.

Fact: This is very unlikely. While poppy seeds used on bagels and baked goods do contain tiny trace amounts of opium alkaloids like morphine and codeine, the quantities are far too small to result in a positive drug test for opiates.

In order to test positive, you would need to eat an extremely large quantity of poppy seeds. Estimates suggest you would need to consume at least 250-500g of poppy seeds to approach the morphine limit and test positive. This would require eating multiple bags of raw poppy seeds – far more than any baked goods contain.

So while poppy seeds do contain miniscule opiate residues, realistically the amounts are too low for drivers to worry about causing false positive roadside drug tests or blood tests after eating poppy seed foods. Using poppy seeds is not a viable legal defence against opiate charges. Consuming regular baked goods will not put you over the legal limits.


Myth #7: Only illegal drugs like cocaine can result in a conviction.

Fact: This is false – legal prescription and over-the-counter drugs are also subject to the drug driving law. Many motorists wrongly believe that only controlled substances like cannabis, cocaine, MDMA and heroin can lead to drug driving charges.

In truth, the law covers many prescription and OTC medications if they are taken in quantities that exceed specified limits for driving. Drugs like diazepam, methadone, codeine and amphetamines are all legally prescribed, but can still result in convictions if you drive over their thresholds and fail to follow medical advice about their use.

For example, common medications like benzodiazepines for anxiety carry potential drug driving penalties. So it’s critical to check the drug’s driving limits before operating a vehicle after taking any substance, even something prescribed by your doctor or purchased at the pharmacy or chemist. Legal medications are also covered under the drug driving law.


Myth #8: Drug testing devices used by police are unreliable.

Fact: The roadside drug testing devices used by police are scientifically reliable and approved by the Home Office drugs branch. Police use something called a “DrugWipe” device for initial roadside screening. This detects and measures drug levels in oral fluid to check for drug driving impairment.

While the roadside device can only give a positive or negative result, it uses reliable immunoassay technology and is calibrated to detect specified drug levels accurately. DrugWipe devices are precise enough for police to legally request a blood sample based on a positive result.

If the blood sample also returns a positive lab result, it confirms the initial roadside screening was correct. These devices would not be Home Office approved for law enforcement usage if they did not reliably detect prohibited drug levels. So claims that the test equipment producing false positives are misguided – the technology is sound.


Myth #9: You can refuse to give a blood sample after a positive drug test.

Fact: Refusing to provide a blood sample for analysis after failing a roadside drug screening can lead to arrest and prosecution for “failure to provide”. This carries the same disqualification periods and fines as a conviction for drug driving.

After a positive DrugWipe test, police can require you to provide a blood sample at a station for lab confirmation. If you refuse to give a sample, you face arrest and prosecution – even if you believe the roadside test was wrong.

The penalties for failing to provide a blood specimen start at a 1-year driving ban if you have no previous drug offences, or 3 years if you have a previous conviction in the last 10 years. However, in failing to provide cases the driving ban starting point is often much longer than the 12 month minimum. Fines are also unlimited.

Given the severe repercussions of refusing to comply, it is always advisable to provide the requested blood sample instead of declining. While you may dispute the accuracy of the roadside device, refusal escalates the matter into a more serious offence carrying harsher punishments.


Myth #10: If you pass a roadside preliminary impairment test, you’ll pass the drug test.

Fact: Passing a preliminary impairment test does not automatically mean you will pass a drug screening. Preliminary impairment tests assess coordination and symptoms of alcohol and drug impairment.

DrugWipes test for the presence of cannabis and cocaine, not whether you are over the limit. A positive test provides the police officer with a suspicion that allows them to arrest you; however, they can also be suspicious that you have used drugs for other reasons. So it is faulty thinking to assume passing a preliminary impairment test means officers have no grounds to drug test you. Police can still administer drug tests even if you passed sobriety exercises.



It’s clear there are many misleading myths around drug driving charges that need to be corrected. While the drug driving laws aim to improve road safety, knowing the facts on testing procedures, legal limits, unreliable defences, and the harsh penalties for convictions is crucial for all drivers. Debunking these 10 common drug driving myths helps shed light on the strict laws around operating vehicles after taking potentially impairing substances.

If you have been charged with drug driving, it is essential to speak to an expert defence solicitor to evaluate the evidence and develop effective strategies specific to your case. At Driving Solicitors, our team has an in-depth understanding of England and Wales’ drug driving laws and experience defending complex cases. Don’t leave your driving future to chance – contact our specialist drug driving solicitors today for advice and legal representation.