Driving Under the Influence and PCA Charges, written by Casey Isaacs

In drink driving cases, once a positive test to the breath analysis instrument has occurred that test is deemed to be correct unless evidence is provided to the contrary.
Over time, legislation has been made increasingly stringent in relation to drink driving charges where effectively once a positive test has been established, a presumption of guilt is created.


Drink driving charges may be challenged if it can be established that drinking occurred after the driving, but prior to the person being required to submit to a breath test or through a blood test. Blood Tests are used to rebut the presumption of guilty.


Those who have been charged with a drink driving offence under the regulations must be provided by police advice as to the availability of a blood test. In such circumstances a blood test kit is provided and one must make their own way to a hospital or by other means to have a registered practitioner and have a sample of their blood taken. One of the blood samples is then retained and the other given back to the person involved.


Of course, if the blood testing occurs a significant period after the actual drink driving then the prior concentration of alcohol reading in the blood is not necessarily utilised, and a special formula is used to work out the concentration at the time of driving. This is colloquially called a BAC calculation.


If the reduction of the alcohol content in the blood is greater than the variances allowed under the regulations, then this may be a basis to challenge the original reading.
Additionally, many may have heard of a blood result being that of denatured. This means that due to some reason, such as the blood being kept in an environment that was too warm, or not enough blood being taken, that the sample is unable to be analysed and the blood alcohol content cannot be determined.


Whist in recent times, if a blood test was denatured, the prosecution would normally withdraw the charges. The Supreme Court has now sought to limit the availability of such defence.


That is until the matter of Dunstall. The background of that case is that the defendant was pulled over on the way home and produced a positive reading. He obtained a blood test kits and obtained two samples. The two samples both came back as denatured.


Expert evidence was led that the reason that the blood test result was denatured was due to the medical practitioner (a nurse) not providing a sufficient sample for analysis. The failure to provide a sufficient sample was in breach of the Road Traffic Regulations.


Consequently, it was determined that the defendant’s rights had been interfered with and was prejudiced by virtue that he could not challenge the original breath analysis reading.


It was therefore determined that that was unfair and the original breath test reading was excluded and a not guilty finding ensured.


The decision has since been upheld by the Supreme Court of South Australia and also the Full Court of Criminal Appeal of South Australia.
The interest by the government is significant, with them seeking leave to appeal to the High Court of Australia.


It seems that the only effective defence available to drivers to challenge the breath analysis reading is now sought to the quashed through the High Court of Australia.

POLICE v DUNSTALL [2014] SASCFC 85 (25 July 2014) refers.

Written by Casey Isaacs