Blood Test Drug Drink Driving NSW

Drink Driving or PCA matters often are difficult matters to defend. Police use specially calibrated instruments to measure the concentration of alcohol present in a person’s breath or blood to determine if the person’s level of intoxication is over the legal limit. Proving those instruments are faulty is unlikely and generally the cost/benefit analysis of progressing down that path doesn’t stack up.

Consequently, most people focus on mitigating the effect of a loss of license after being charged with PCA offences, rather than beating the charge.

However, a recent High Court of Australia case has confirmed there are defenses that can be utilised to defeat a charge of drink driving and they are more likely to stack up when put to the cost/benefit analysis.

In this case, a medical practitioner failed to take a blood sample in accordance with the prescribed procedures such that it could not be relied upon. The issue for the court was in a situation where the driver effectively had lost the statutory right to have a sample of his blood tested by a medical practitioner, did the court have a discretion to exclude the lawfully obtained breath analysis test results where admission of the evidence would render the trial of the defendant unfair.


Jason Dunstall was stopped by police while he was driving a motor vehicle in suburban Adelaide. He submitted to an ‘alcotest’ (breathalyzer), which returned a positive result. He was taken to a police station, at which he provided a sample of his breath for analysis. His breath analysis reading was 0.155 grams of alcohol per 100 millilitres of his blood. Mr Dunstall was informed of his right to have a sample of his blood taken for analysis and he was supplied with a blood test kit. The police drove Mr Dunstall to the Noarlunga Hospital, where a medical practitioner took a sample of his blood. Later attempts to analyse the sample proved unsuccessful.

Mr Dunstall was charged with driving a motor vehicle when there was present in his blood the prescribed concentration of alcohol. He pleaded not guilty to the charge in the Magistrates Court of South Australia (Magistrate Dixon). At the hearing, over Mr Dunstall’s objection, a certificate recording the breath analysis reading was admitted in evidence. Further certificates were tendered in the prosecution case to establish that the operator was authorised and that the requirements and procedures relating to breath analysing instruments and breath analysis under the RTA. The medical practitioner who took the blood sample was called in the prosecution case. She had no memory of taking the sample and no knowledge of how the sample had come to be unusable.

Mr Collins, a forensic pathologist, was called in the defence case. Mr Collins considered that the likely explanation for the sample being unable to be analysed was that an insufficient quantity of blood had been taken from Mr Dunstall. Magistrate Dixon found that the blood sample was unsuitable for analysis because the medical practitioner had not taken a sufficiently large quantity of blood.


In South Australia (similar provisions are also found in NSW legislation) proof of a drink driving offence is facilitated by a statutory presumption that the concentration of alcohol indicated by a breath analysing instrument as being present in the driver’s blood was the concentration of alcohol in the driver’s blood at the time of the breath analysis and throughout the preceding period of two hours (“the presumption”).

The presumption may only be rebutted if a person who returns a positive result arranges for a sample of his or her blood to be taken by a medical practitioner that proves that the breath analysing instrument gave an exaggerated reading.

As the blood test could not be relied upon, Police relied solely on the earlier breath analysis.

The issue raised by the appeal to the High Court was whether, in a case in which a medical practitioner fails to take the blood sample in accordance with the prescribed procedures, the court has a discretion to exclude evidence on the ground that admission of the evidence would render the trial of the defendant unfair.


Initially the Local Court, Supreme Court and Full Court of the Supreme Court excluded evidence on the ground that admission of the evidence would render the trial of the defendant unfair and dismissed the charges.

The High Court however found that it was not open to conclude that admission of the breath analysis test certificate would cause an unacceptable risk of a miscarriage of justice and therefore the breath analysis test certificate should not be excluded.

The Court found that there was no unfairness in the prosecution’s reliance on the breath analysis in circumstances where the doctor’s error deprived Mr Dunstall of the ability to obtain admissible blood test evidence.

The High Court determined that although a loss of evidence may provide grounds to stay (discontinue) the prosecution of a criminal case if the absence of the evidence constituted an unacceptable risk of injustice or unfairness, this will only occur in limited circumstances. A stay is the last resort because it runs counter to the requirement that a suspected offender be brought to trial.

In this matter, the breath analysis remained legally obtained evidence that could be used by police in the prosecution of the matter. The breath analysis could also be argued against by the defendant. If, the only evidence relied upon by police was the blood test, it would have been more difficult for the police to prove that there was no risk of injustice or unfairness as in those circumstances the only evidence could not be tested by the defendant.

As the High Court found that there was not an unacceptable risk of injustice or unfairness to Mr Dunstall the matter was returned to the Magistrates Court for a new hearing.

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