About Drug Driving

What is Drug Driving?

Although similar to drink driving in terms of penalties, drug driving is tested differently and it lacks clearly defined legal limits. Drug driving is the offence of getting behind the wheel of a vehicle while under the influence of any substance or substances that are likely to impair the ability to drive. Both legal and illegal substances can be covered.


The penalties for drug driving are the same as for drink driving.

Someone convicted of drug driving will receive:

  • A driving ban of at least 12 months.

  • A criminal record.

  • A note on their driving licence for 11 years detailing a conviction for drug driving which their employer will see if they drive for work.

  • A fine up to a maximum of £5,000.

In addition to the above, having a drug-related conviction can make entering certain countries difficult (e.g. the USA) and it will increase the cost of car insurance dramatically.

  • If a driver causes a fatal accident while under the influence of drugs, they could face a sentence of up to 14 years in jail.


The police can stop any driver they suspect of drug driving and test them by the roadside. As well as administering the Field Impairment Assessment to test co-ordination skills, they can check the driver’s eyes for signs of drug use, which may involve using a pupil measure. Refusal to participate in the tests is an offence.

The five tests a driver is likely to be required to take are:

  1. The Pupil Measure Test – eyes are examined for pupil size, condition (e.g. larger blood vessels/bloodshot appearance) and reactions to light.

  2. The Romberg Test – the subject must tilt their head back, close their eyes and estimate when 30 seconds have passed.

  3. The Walk and Turn Test – the subject must walk heel to toe in a straight line while looking at their feet and counting their steps out loud.

  4. The One Leg Stand Test – the subject must count out loud while standing on one leg.

  5. The Finger to Nose Test – the subject must tilt their head back, close their eyes and touch the tip of their nose with the tip of a finger on the hand selected by the police officer.

As yet, there is no drug-specific alternative to the breathalyser, but if the roadside tests lead the police to believe that the driver may be under the influence of drugs, they can arrest them and take them to a police station. At the police station, the driver can be subjected to biological testing such as urine testing or blood testing. These tests can be performed even if the driver is unconscious.


Unlike alcohol, there is no definitive legal limit for drugs because it is very difficult to ascertain how different drugs impair different people’s ability to drive. As a result, cases can become far more complicated and open to interpretation than drink driving cases. The law is currently restricted to being able to prosecute only where the police can prove that a person is incapable of driving because of drugs.

The Future

Increasing pressure from driving and road safety groups has led to the law coming under review and tougher measures to deal with drug driving look likely.