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Frequently Asked Questions

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If you take drugs and drive you may be guilty of the following offences:

  1. being unfit to drive through drink or drugs;
  2. being over the prescribed limit in relation to the levels of specified drugs your blood – you can commit this offence even if your driving is unaffected by the drugs.
In relation to both offences, if the police suspect you have been taking drugs and you are driving, attempting to drive or are in charge of a mechanically propelled vehicle (offence 1) or a motor vehicle (offence 2) on a road or public place, they have the power to require you to take a field impairment assessment or drug test. A field impairment assessment consists of a series of tests e.g. touching the tip of your nose with the tip of your finger whilst your eyes are closed, that are designed to see if drugs are affecting your ability to drive properly. A drugs test uses a specimen of sweat or saliva to detect the presence of a drugs. If you perform poorly in the field impairment assessment or give a positive drugs test or you fail/refuse to take either test and the police officer suspects drugs, you can be arrested and taken to the police station. There, further tests and medical examinations will be carried out and you could ultimately be prosecuted for being:
  1. Unfit through drugs – note there are no lists of specified drugs or set levels in relation to this offence but the police must prove that you are unfit to drive. Unfit means that your ability to drive properly is for the time being impaired.
  2. Over the prescribed limit in relation to specified drugs – note there are specified drugs and set levels in relation to this offence – see tables below.

The law specifies eight illegal drugs and nine medicinal drugs (drugs used in medicines) – these are shown together with the corresponding levels in the tables below:

The units µg /L mean micrograms per litre.

If you are caught driving, attempting to drive or in charge of a vehicle with levels of illegal drugs above those shown in the Table 1, you will commit an offence. If you have been prescribed medication that contains any of the drugs listed in Table 2 or if you are unsure about whether your medication contains any of these drugs, you should talk to your doctor about whether it's alright for you to drive – you can still drive after taking the medicinal drugs listed in table 2 if:

  • you've been prescribed them and are following medical advice on how to take them;
  • they aren't causing you to be unfit to drive, even if you're above the specified limits

The units of the thresholds are µg /L or micrograms per litre - it's important to realise that even relatively small amounts of the drugs can put you over the threshold. Note that the police cannot give you any advice on the dosage that would put you over the specified limits or how long after taking a drug you must wait before you a safe to drive. The reason for this is that there are just too many variables, everyone metabolises drugs differently and factors such as you height, weight and what you have had to eat will all play a part.

If you are convicted of drug driving you:

  • may lose your job/independence;
  • may have difficulty entering countries like America;
  • will face a substantial increase in the cost of your car insurance;
  • will have a criminal record.

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Answers in this FAQ section are provided by the 'Ask the Police' website. Produced by the Police National Legal Database (PNLD) team, 'Ask the Police' is an official police site approved by the National Police Chiefs Council (NPCC). All FAQ answers are © PNLD.