Drink driving test: overview of breath, blood & urine testing
(1) Preliminary test
As a preliminary step in most drink driving investigations, the police administer a breath test and/or a sobriety/impairment test at the roadside. The law only permits a uniformed constable to perform these tests, not a plain clothes officer.
Moreover, the constable may only initiate testing if they have 'reasonable cause' to suspect that a person has either consumed alcohol or committed a traffic offence.
If the suspect fails to submit to a drink driving test or the test shows a breath alcohol level above 35 microgrammes (mg), the police may arrest him or her.
To actually prove that the suspect has committed a drink driving offence, however, the police must take him or her back to the police station and carry out additional testing.
(NB. This is because the police use hand-held breathalysers for roadside stops, which sometimes provide inaccurate results, and since the results cannot be relied on, they are not admissible as evidence in court proceedings.)
(2) Additional tests
Once back at the station, the police will usually ask the suspect to provide two additional breath specimens using a larger evidential breath testing device. The lower reading of the two breath specimens should be used and the other ignored.
If the lower of the two breath specimens is no more than 50 mg, the suspect may request that a sample of blood or urine be taken. The decision as to which of the two is taken is made by the police constable. This sample is then used to establish whether an offence has been committed and the earlier breath tests are ignored.
Crown Prosecution Service guidance on drink driving offences states that although the prescribed breath alcohol limit is 35 mg, a driver will not be prosecuted with a breath alcohol level of less than 40 mg.
Blood and urine testing
As mentioned above, if the breath specimen is no more than 50 mg, a suspect may request that a sample of blood or urine be taken. This is because blood and urine tests are widely considered to be more accurate than breath tests in assessing blood alcohol levels.
The police may also request a blood or urine test if the suspect is unable to provide a breath specimen because of some medical condition (e.g., severe asthma or emphysema).
The prescribed limit for alcohol in the blood is 80 mg per 100 millilitres (ml) of blood. For urine, it is 107 mg per 100 ml of urine.
Failure to provide a test sample
If a suspect fails to provide a test sample when legally required to do so, he or she may face criminal prosecution. Three offences exist:
- Failure to co-operate with a preliminary test: a person commits this offence by failing to submit to a roadside breathalyser test or sobriety/impairment test. The maximum penalty for this offence includes four penalty points (to remain on your licence for four years) or a 12-36 month driving disqualification and a £1,000 fine.
- Failing to provide an evidential specimen for analysis: a person commits this offence by failing to provide breath, blood or urine samples at the police station. The maximum penalty for this offence varies depending on whether the offender failed to provide a specimen after either 'driving/attempting to drive' or being 'in charge' of a vehicle.
- The penalty for failing to provide a specimen for analysis after driving/attempting to drive is 3-11 penalty points (to remain on your licence for 11 years) or a 12-36 month driving disqualification, a £5,000 fine, and six months imprisonment.
- The penalty for failing to provide a specimen for analysis after being arrested in charge of a vehicle is less severe: 10 penalty points (to remain on your licence for four years) or a 12-36 month disqualification, a £2,500 fine, and three months imprisonment.
- Failing to give permission for laboratory test: if a specimen is taken, it cannot be subjected to a laboratory test unless the person from whom it was taken expressly agrees. The maximum penalty for this offence is identical to those for 'failing to provide an evidential specimen for analysis' (discussed above).
A suspect may fail to provide a test sample if he or she has a "reasonable excuse". This usually requires production of med ical evidence about some kind of physical or mental infirmity.
In one case, a court found the accused's shortness of breath during a panic attack to be a reasonable excuse for failing to provide a breath specimen. In another, however, the court said aversion to the sight of blood did not excuse the accused from giving blood (since he could either shut his eyes or look away as blood was drawn).
The courts have also affirmed that waiting for legal advice does not constitute a reasonable excuse for failing to take a test unless a solicitor is immediately available, either in person or by telephone, "for a couple of minutes" and any delay in the test would be "very short".
Finally, even if the police act in bad faith and the accused did not drive, attempt to drive, or take charge of a vehicle, he or she would not have a reasonable excuse to refuse a test.
Should I Consult a Solicitor?
If you've been charged with a drink driving related offence, you need to consider your position very carefully as the penalties can be severe. In every case, you are strongly advised to seek legal advice. You can find a criminal law solicitor in your area via Contact Law.
- Drink driving law overview
- Drink driving FAQs
- Drink driving penalties
- Failure to provide a roadside breath test
- What is the drink driving limit?
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