It is not possible to challenge the results of a breath test taken within 3 hours of driving without a blood test. There is a presumption that the breath test blood alcohol concentration ('BAC') result is the BAC of the person for the 3 hours prior to the breath test [Road Traffic Act 1961 (SA) s 47K(1)]. This presumption can be rebutted by proof to the contrary.

Legal advice should be sought if the breath test is taken more than 3 hours after driving, especially if the driver has consumed alcohol after driving but before the breath test is taken. It may be possible to challenge the results of the breath test relied on for a DUI or PCA offence where [s 47GA]:

It will be a question of whether the driver is believed that any alcohol was consumed after the driving and what effect that alcohol had on the driver's blood alcohol level. It is possible that the court may find the driver guilty of a lesser offence (instead of an alcohol level of 0.15 BAC the court may decide the reading should be 0.09 BAC or may find the driver not guilty).

Prior to 12 December 2022, time limit applicable under section 47GA was from the time of the driving until the breath test was taken. It is now only available from 3 hours after driving or a driving incident until the breath test is taken.

As a result of the 2022 change, it is best practice that drivers do not consume any alcohol within 3 hours of any known driving incident, such as an accident, in case they are required to submit to a breath test during that time - the presumption means it may be impossible to have subsequent alcohol consumption taken into account.