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Field impairment test

Rules and regulations

What is a Field Impairment Test?

The Field Impairment Test or Assessment is a way for police to check drivers for impairment through intoxication. The breathalyser has been used to test for alcohol for years but until very recently, there was no technology available to police for roadside drugs testing.

The Field Impairment Test

  1. Pupil measure test

    • Pupil size
    • Pupil condition
    • Reaction to light

    Some drugs cause pupils to shrink or enlarge, and this can be checked against a card to indicate abnormal size.

  2. Romberg test

    • Stand still
    • Tilt head back
    • Count 30 seconds

    This checks balance and judgement of time - both of which can be impaired by various substances.

  3. Walk and turn test

    • Walk along a straight line, stepping heel to toe
    • Count steps out loud while watching feet

    Stumbling or stepping off the line can indicate impairment.

  4. One leg stand test

    • Stand on one leg
    • Count out loud

    An intoxicated driver may sway or lose balance.

  5. Finger to nose test

    • Tilt head back with eyes closed
    • Touch finger to nose using the hand indicated

    This tests co-ordination, which some drugs can throw off.

What happens if I fail the Field Impairment Test?

If a police officer suspects that you are driving impaired under the influence of drugs (illegal or prescription) because of how you performed in the test, they can decide to arrest you.

You would then be asked to give a urine, blood or saliva sample at a police station. This is checked for drugs and can be used to secure a drug driving conviction - but refusal to give a sample is also an offence and you can still be convicted of drug driving.

Scary? Yup. So be warned!


Find the list of 16 drugs that will be subject to new legal drive limits.