i) Although the legal limit is 35 microgrammes, the police only prosecute if you blow 40 microgrammes or more in 100 millilitres of breath.
ii) The roadside breath test, if one is demanded and given, is purely a screening test and does not prove in itself that you were over the drink driving limit. To prove this the police must take you to a police station and there obtain from you, two samples of breath on an Evidential Breath Testing Machine (EBTM), or a sample of blood or urine.
iii) You have no automatic right to have a sample of breath replaced with a sample of blood or urine. The taking of such alternative samples sample is now a more rare event than previously, following the ending of a suspects right to have breath replaced with blood or, urine when he or she blew between 40 and 50 on the EBTM.
iv) It is vital – if the police are going to prove their case – that they follow correct procedures to the letter.
v) During the evidential procedure on the EBTM, the police will ask you at least 17 questions and give you instructions as to how to blow into the machine. If the police foul up or make mistakes during the procedure then that may, depending upon the seriousness of such mistake, lead to an automatic acquittal. Hence the truly vital need for your lawyer to obtain, and study, the CCTV record of what happened during the evidential procedure. Your guilt or innocence could hang upon the contents of that recording.