Driving Whilst Unfit Through Drugs - Client Practice Note


From 2 March 2015 a new criminal offence of driving or attempting to drive a vehicle if unfit through drugs became law. The law applies if any of 16 controlled substances are detected above certain limits in the driver's blood.

The relevant offences include:

  • Drink-driving

  • Attempting to drive

  • Being in charge of a vehicle

The penalties are similar to those for the conventional drink-driving offence and include

  • A one year mandatory driving ban

  • Unlimited fine

  • Maximum of six months imprisonment

The drivers licence will also be endorsed, with a record kept for up to 11 years.

Insurance costs will escalate for anyone convicted of this offence and, as with any criminal conviction, those affected may find it more difficult than otherwise to obtain travel documents to visit certain countries, including the USA.

The new laws are designed to be more effective than other provisions covering the same conduct which also exist, requiring the Prosecution to prove that a driver’s ability to control a vehicle was impaired because of the drugs in their system.

The new offence is triggered if the results of a drug analysis of a blood sample from a driver reveals DDR  above specified limits. It is therefore much easier to prove as the Prosecution do not need to show that a drivers ability was impaired.

At the roadside, officers will now be equipped with a roadside drugs kit that will enable them to screen drivers for cannabis and cocaine. If these tests return positive results, drivers will be taken to a police station to provide a blood sample.


It is a defence for a driver to show that he has been prescribed a specific drug for medical or dental purposes and they have taken in accordance with the manufactures instruction. In addition, evidence will be required to demonstrate that a drivers ability  was not consequently impaired.

However, anyone who ignores medical advice as to the how long they should wait after taking drugs before driving may find that they have no defence in law. Each case will be determined on its own facts.

Prohibited Substances

The list of drugs includes prohibited substances such as speed, cannabis and cocaine. The legal threshold is set at a very low specified limit. A number of prescription drugs  also features on the list (with higher thresholds) including diazepam.