If you take prescription drugs, you may wonder whether you are legally allowed to drive.
UK drug driving laws distinguish between certain controlled drugs that have specified limits and the broader offence of driving while unfit to drive because of drugs. This means that simply having a prescription does not automatically make it legal to drive if the medication is affecting your ability to drive safely.
The rules can be particularly confusing because some prescription medicines are covered by statutory drug limits, while others are not. Understanding the distinction is important if you are taking medication and need to drive.
Is It Legal To Drive On Prescription Drugs?
The law does not make it automatically illegal to drive simply because you have prescription drugs in your system.
However, there are two important issues to understand.
First, it is an offence to drive while unfit through drugs, including legal prescription medication, if the drugs have impaired your ability to drive.
Second, there is a separate offence under section 5A of the Road Traffic Act 1988 involving certain specified controlled drugs being present in your blood above specified limits. This offence can apply even where the drug has not affected your driving.
There is, however, a specific medical defence for certain prescription drugs.
What Is Drug Driving?
Drug driving is a broad term used to describe several different offences.
Under the Road Traffic Act 1988, it is illegal to drive if:
- You are unfit to drive because of drugs, whether they are legal or illegal; or
- You have certain levels of a specified controlled drug in your blood and the relevant statutory requirements are met.
The second offence is sometimes described as the “over the specified limit” offence.
This distinction is important because you do not necessarily have to demonstrate obvious impairment to prosecute someone under the specified-limit offence.
The government explains that drivers can be prosecuted where their blood contains certain illegal drugs above the specified limits, even if those drugs have not affected their driving.
Which Prescription Drugs Have Specified Limits?
A number of prescription drugs are subject to specified limits.
These include:
- Clonazepam
- Diazepam
- Flunitrazepam
- Lorazepam
- Methadone
- Morphine
- Oxazepam
- Temazepam
- Amphetamine, including medicines such as dexamphetamine and selegiline
There are different limits depending on the drug. For example, the government lists blood limits of 50µg/L for clonazepam, 550µg/L for diazepam, 80µg/L for morphine and 1,000µg/L for temazepam. Amphetamine is treated separately, with a specified limit of 250µg/L.
The fact that a drug has a specified limit does not mean that taking more than a particular prescribed dose automatically results in being over the limit. Blood concentrations can vary considerably between individuals, and the government warns that it cannot provide dosage equivalents for the specified limits.
What Is The Medical Defence?
One of the most important protections for people taking prescribed medication is the medical defence.
Under section 5A of the Road Traffic Act 1988, a person can have a defence where the specified controlled drug was prescribed or supplied for medical or dental purposes and was taken in accordance with medical advice.
The Crown Prosecution Service confirms that the defence applies where the drug was prescribed or supplied in accordance with the Misuse of Drugs Act 1971 and taken in accordance with medical advice. The defence is not available where the medical advice has not been followed.
However, this does not mean you can drive regardless of how the medication affects you.
If your prescribed medication makes you unfit to drive, you could still face prosecution under the separate offence of driving while unfit through drugs.
For example
Imagine you have been prescribed diazepam and take it exactly as directed.
If your blood concentration is above the relevant specified limit, the medical defence may be available where the medication was properly prescribed and taken in accordance with medical advice.
However, if the medication significantly affects your ability to drive and you are clearly impaired, having a prescription does not necessarily protect you from prosecution.
This is why it is important to follow your doctor’s or pharmacist’s instructions and pay attention to warnings about driving.
What Does “Unfit To Drive” Mean?
Being unfit to drive because of drugs is different from simply having a drug in your system.
The question is whether your ability to drive has been impaired to such an extent that you are not capable of driving properly.
Police may look for signs such as:
- Poor concentration
- Slow reactions
- Confusion
- Poor coordination
- Unusual behaviour
- Difficulty following instructions
- Erratic driving
- Difficulty maintaining a straight line
- Other evidence suggesting impairment
The government states that police can carry out a field impairment assessment where they suspect a driver is affected by drugs. This can include asking the driver to walk in a straight line.
Can You Be Arrested For Driving On Prescription Medication?
Yes, if the police suspect that you are unfit to drive because of medication or another drug.
Police can stop a driver and carry out a roadside test. Drug screening equipment can test for substances including cannabis and cocaine.
If officers believe that you may be impaired, you can be arrested and taken to a police station, where you may be required to provide a blood or urine test.
The evidential sample is then analysed, and the results may form part of the prosecution evidence.
What Happens At The Police Station?
If you are arrested on suspicion of drug driving, you may be required to provide a specimen for analysis.
Depending on the circumstances, this may involve providing a blood sample or urine sample.
Laboratory analysis can establish the concentration of a particular drug in the sample. For specified controlled drugs, the result may be compared with the relevant statutory limit.
For an allegation of driving while unfit, the prosecution will also consider evidence relating to the driver’s impairment.
This means that a drug test result should not necessarily be viewed in isolation. The precise offence being alleged and the evidence supporting it are important.
What About Illegal Drugs?
The law also applies to illegal drugs, including substances such as cocaine and cannabis.
There is no equivalent medical defence for illegal recreational drug use.
If a driver has a specified illegal drug in their blood above the relevant limit, they can face prosecution under the specified-limit offence.
Alternatively, where drug use has impaired driving, the driver may face prosecution for being unfit to drive.
The government specifically identifies cannabis and cocaine as drugs that can be screened for using roadside drug testing equipment.
What If You Take Someone Else’s Medication?
Taking someone else’s medication can create significant legal and safety issues.
The medical defence is intended for drugs that have been prescribed or supplied to the defendant for medical or dental purposes and taken in accordance with medical advice.
Taking another person’s prescription medication would not ordinarily satisfy those requirements.
This can be particularly important where a person has taken a controlled drug without realising its potential effect on their ability to drive.
If you have been accused of drug driving after taking someone else’s medication, specialist legal advice should be obtained as soon as possible.
What About Over-The-Counter Medicines?
Drug driving law is not limited to controlled prescription medication.
Some over-the-counter medicines can affect concentration, reaction times or alertness.
The government advises drivers who are unsure whether they should drive after taking legal drugs to speak to a doctor, pharmacist or other healthcare professional.
You should also read the manufacturer’s instructions and patient information leaflet before driving.
Warnings such as “may cause drowsiness” should be taken seriously.
What If Medication Interacts With A Medical Condition?
Your medical condition can also be relevant to your ability to drive.
A driver may be prosecuted where their driving is impaired by a medical condition, particularly where they have ignored medical advice about driving.
This can overlap with cases involving medication.
For example, if a healthcare professional has warned you not to drive because of the effects of a particular medication, ignoring that advice could become relevant to the prosecution case.
The Sentencing Council’s driving guidelines also identify driving while significantly impaired by a known medical condition, or disregarding advice relating to the effect of a medical condition or medication, as a relevant culpability factor in serious driving cases.
What Are The Penalties For Drug Driving?
Being convicted of drug driving can have serious consequences.
The government states that the penalties can include:
- A minimum one-year driving ban
- An unlimited fine
- Up to six months in prison
- A criminal record
- A conviction endorsement on your driving licence lasting for 11 years
There can also be significant practical consequences.
For example, a conviction can result in increased car insurance costs, and some drivers may face difficulties travelling to certain countries.
For people who depend on their vehicle for employment, losing their driving licence can also have a substantial financial impact.
Can You Receive A Community Order For Drug Driving?
Yes, depending on the circumstances.
Not every drug driving conviction results in immediate imprisonment. The court considers the facts of the offence and the relevant sentencing framework when determining the appropriate penalty.
A community order can be available in appropriate cases, although the court will consider the seriousness of the offence and any aggravating or mitigating circumstances.
Previous convictions, the level of impairment and the circumstances surrounding the offence can all be relevant.
What If Drug Driving Causes Death?
Cases where drugs contribute to a fatal collision can result in significantly more serious charges.
For example, causing death by careless driving whilst under the influence of drink or drugs is a separate offence under section 3A of the Road Traffic Act 1988.
For offences committed after 28 June 2022, the maximum penalty is life imprisonment, with the Sentencing Council guideline providing an offence range of 26 weeks to 18 years’ custody.
There is also the separate offence of causing death by dangerous driving. For offences committed after 28 June 2022, the maximum penalty is also life imprisonment, with a guideline offence range of two to 18 years’ custody.
These are extremely serious cases and require specialist legal representation.
What Evidence Can Be Used In A Drug Driving Case?
A prosecution can rely on several different types of evidence, depending on the offence.
This may include:
- Roadside drug test results
- Field impairment assessment evidence
- Blood or urine analysis
- Laboratory evidence
- Police officer observations
- Driving behaviour
- Statements from witnesses
- Medical records
- Prescription information
- Evidence from your doctor or other healthcare professional
- Evidence concerning the circumstances in which the medication was taken
The Forensic Science Regulator has published guidance concerning the use of legal limits in drug driving prosecutions, reflecting the importance of scientific evidence in these cases.
What Should You Do If You Are Accused Of Drug Driving?
If you have been arrested or charged with drug driving, it is important to obtain legal advice promptly.
You should retain relevant information about any prescription drugs you were taking, including:
- Your prescription
- Medication packaging
- Dosage instructions
- Patient information leaflets
- Records of when you took the medication
- Advice provided by your doctor or pharmacist
Do not assume that having a prescription automatically means the allegation will be dismissed.
Equally, do not assume that a positive blood test automatically means you are guilty.
The precise drug, concentration, circumstances in which it was taken and the offence being prosecuted all matter.
Expert Drug Driving Solicitors At McArthur Solicitors
Being accused of drug driving does not necessarily mean that you are guilty. Cases involving prescription medication can be particularly complex because the law recognises a medical defence in certain circumstances, while still making it an offence to drive when medication has made you unfit.
At McArthur Solicitors, our criminal defence team has experience dealing with driving offences and can advise you on the circumstances surrounding your allegation. We can examine the evidence, including drug testing and medical evidence, advise on the available defences and represent you throughout the criminal justice process.
Whether you have been stopped following a roadside test, arrested at a police station, charged after a blood test or are facing serious allegations involving causing death, obtaining specialist legal advice early can be crucial.
If you are facing a drug driving allegation, contact McArthur Solicitors today for expert criminal defence advice and representation.
