Drug driving with prescribed medication

This is an important question and the answer is nuanced. Yes, you can be convicted of drug driving even if the drugs were prescribed medication, but there is a specific statutory defence available to you.

The legal framework:

Drug driving is governed by section 5A of the Road Traffic Act 1988, which was inserted by the Crime and Courts Act 2013 and came into force in March 2015. It creates an offence of driving or being in charge of a motor vehicle with a specified controlled drug in the body above the specified limit. The specified drugs and their limits are set out in The Drug Driving (Specified Limits) (England and Wales) Regulations 2014.

The regulations set limits for 17 drugs split into two groups. The first group covers drugs more commonly associated with medical use, such as morphine, diazepam, clonazepam, oxazepam, lorazepam, temazepam, and methadone. For these drugs the limits were deliberately set at higher levels to try to avoid catching people taking normal therapeutic doses. The second group covers drugs more commonly associated with illicit use, such as cannabis, cocaine, ketamine, and MDMA, where the limits are set very low, essentially at just above accidental exposure levels.

The statutory medical defence:

Section 5A(3) provides a defence if you can show that the specified controlled drug had been prescribed or supplied to you for medical or dental purposes, and that you took the drug in accordance with any directions given by the prescriber or any accompanying instructions. This means you must have been taking it as directed. If, for example, you were taking a higher dose than prescribed, or combining it with alcohol or other substances in a way that was not part of your medical directions, the defence may not be available.

The burden of proof on this defence is on the defendant, but only on the balance of probabilities, meaning you need to show it was more likely than not that you were taking the drug as prescribed.

Important practical points:

1. This defence does not apply to the separate offence of driving while impaired under section 4 of the Road Traffic Act 1988. If your driving is actually impaired by prescribed medication, you can still be prosecuted under section 4 regardless of whether you had a prescription and were taking it correctly. The police and CPS can choose which charge to bring.

2. Even if you are below the specified limit or have a valid medical defence to a section 5A charge, you could still be convicted under section 4 if the prosecution proves your driving was impaired. This is an important distinction that people often miss.

3. The fact that a drug was prescribed does not automatically mean you are safe to drive. Many prescribed medications carry warnings about driving. Your prescriber should advise you, and you should check the patient information leaflet. If the medication says you should not drive or should be cautious, that is highly relevant to any impairment charge.

4. If you are stopped and tested, it is important to tell the police at the time that you are taking prescribed medication. Keep your prescription details, pharmacy labels, and any directions easily accessible.

5. If you are charged under section 5A and wish to rely on the medical defence, you will need evidence of the prescription, the dosage directions, and that you were complying with them. Pharmacy records, GP records, and the medication packaging can all be relevant.

What this means in practice:

If you are taking prescribed medication at the correct dose, are not combining it with anything that undermines the prescription regime, and are not actually impaired, you are in a strong position. The section 5A limits for medical drugs were deliberately set to accommodate normal therapeutic use.

However, if you are driving while genuinely impaired by your medication, whether or not it is prescribed, you are at real risk of prosecution under section 4 and the prescription provides no defence to that charge. The law expects you to assess whether you are fit to drive, just as it does with fatigue or any other condition.

If you are facing a charge or investigation in relation to this, the specific facts matter greatly, including which drug, what level was detected, whether the charge is under section 4 or section 5A, and what the circumstances of your driving were.