Are random breath tests or drug tests legal?

Random stop for breath test or drug test

It’s official, the Christmas crackdown on drink and drug drivers has begun. This time of year sees hundreds of unsuspecting motorists caught with too much alcohol or drugs in their system after a random stop by police. But are random breath tests and random drug tests legal?

We could all be stopped in the run up to Christmas. What happens next could determine whether or not you spend the next few hours in a cell, and ultimately, whether you lose your driving licence. What are your rights? What are you compelled to do? How can you avoid being arrested? This article seeks to help address all of these questions.

Can the police stop you at random?

Yes. The law gives the police a general power to you under Section 163 Road Traffic Act 1988. The police can, at random, stop any vehicle without any particular reason.

Can the police make you take a roadside breath test or a drug test at random?

No. Whilst you can be stopped at random by a police officer, they cannot require you take a roadside drink or drugs test without first having reasonable cause to suspect the you, the driver, of having consumed alcohol, drugs or committing a traffic offence when the vehicle was moving. If for example the officer asks you “when was the last time you drank alcohol/ took drugs” and you answer “Dinner time today” this may give rise to a suspicion that you are under the influence, in which case a roadside specimen can be requested from you. Failing or refusing the test would then lead to you being arrested and taken to the police station for evidential testing.

Are there any exceptions?

Yes. An exception exists where there has been an accident. A police officer can ask you to take a roadside drink or drug test where they reasonably believe that you were driving or in charge of a vehicle that has been involved in an accident, whether or not another vehicle was involved.

Can you refuse to take a roadside breath test or drug swab?

driver refusing to take a roadside  breath drive test

Not without a reasonable excuse. Failing to take a roadside test without reasonable excuse is an offence which will result in you being brought to the police station for evidential testing in much the same way that a positive test would have done.


The police can randomly stop your vehicle; however they need reasonable cause to require you to participate in a roadside breath test or drug swab. If you don’t give the officer any reason to believe you may be under the influence, they cannot require you to participate in the test. Keep in mind that over the Christmas period, forces up and down the country are conducting random stops on motorists, and many drivers are ultimately charged with drink driving or drug driving as a result of these random stops.

Our best advice is common sense; make alternative arrangements to return home after a night’s indulgences and do not drive until you are certain you are fit to do so. Bear in mind that this could be well into the afternoon the following day for alcohol, or even several days later in the case of drugs, such as cocaine.

What if I’ve already been pulled over for drink driving or drug driving?

If you’ve already been arrested for drink or drug driving and need advice on what happens next, feel free to contact our free legal advice line on 0330 33 22 770. One of our specialist drink or drug drive lawyers will listen to the details of your case, advise on your options and let you know the best course of action. Whether you need to minimise the effects of a ban or fight the conviction altogether, rest assured we can help.

Article written by Alison Ashworth, Specialist drink and drug driving solicitor and Managing Director of Ashworth Motoring Law. Alison has a first-class honours degree in law and has appeared on various TV and Radio programs to discuss drink and drug driving. Widely considered the “go-to” expert in the field of motoring law, Alison has outstanding rates of securing not guilty verdicts in cases involving drink and drug driving. If you would like Alison to personally look into your case, please call our advice line on 0330 33 22 770 and ask to be transferred directly to her.

Motoring Lawyer Alison Ashworth being interviewed on TV