A specimen of breath for analysis taken from a person suspected of drunken driving. It is this specimen that usually forms the evidence for a prosecution and conviction for offences of drunken driving and should not be confused with the preliminary breath test. The specimen may be required whenever the police are investigating any of these offences, but only if the suspect is at the police station. Usually he will have been brought to the station under arrest as a result of a positive breath test or refusal to undergo such a test. It is an offence not to provide a specimen without a reasonable excuse, and the police officer should warn a suspect of this when asking for the specimen. This offence is punishable by fine or imprisonment, endorsement (which carries 10 penalty points under the totting-up system), and discretionary disqualification (in cases of being in charge of a vehicle) or compulsory disqualification (in cases of driving or attempting to drive).
The suspect must give two breath specimens, which should be measured by means of an approved electronic device (not the breathalyser used for the preliminary breath test) that automatically prints out the level of alcohol in the breath. A print-out of the lower of the two readings is used as evidence in a subsequent trial, together with a signed certificate by a police officer that it refers to the defendant's specimen given at the stated time (Road Traffic Act 1988 s 8). The defendant must be given a copy of these documents at least seven days before his trial, and he may serve notice not later than three days before the trial that he requires the police officer who signed it to attend the hearing. At his trial, a defendant may bring evidence to show that he drank more alcohol between the time of the alleged offence and giving the specimen and that this accounted for his exceeding the prescribed limit. It is an offence, however, to deliberately drink more alcohol in order to make it difficult to prove his guilt.
Once a suspect has given a specimen he is free to leave the police station, but the police may detain him if they reasonably suspect that he is likely to continue driving with an excess alcohol level or while unfit to drive. Under certain circumstances the suspect can provide either a specimen of blood or a specimen of urine instead of a breath specimen. If the breath specimen records a reading of more than 35 but less than 50 micrograms of alcohol per 100 ml of breath (and prosecution is intended), the suspect is entitled to ask that it should be replaced by a blood or urine specimen.