In the South African legal landscape, breathalyzer tests have become a standard method for determining whether a driver is under the influence of alcohol. However, questions about the accuracy and reliability of these tests, particularly in the context of scientific and procedural standards, have come under scrutiny.
A notable case that sheds light on these issues, S v Hendricks the High Court examined the validity of the Drager Alcotest breathalyzer device used in South Africa.
On 23 January 2010, the accused was alleged to have driven a motor vehicle on Greinhout Street, Kewtown Athlone, with a breath alcohol concentration of 0.24 milligrams of alcohol per 1000 millilitres. This concentration allegedly exceeded the legal limit, prompting the use of a breathalyzer to substantiate the charge.
Several key issues were raised regarding the breathalyzer test's reliability:
1. Functionality and Operation: Questions were raised about whether the Drager Alcotest was functioning correctly and whether it was operated by a qualified individual. There were
concerns about whether the device was properly calibrated and capable of accurately
distinguishing between ethyl alcohol and other substances.
2. Calibration and Maintenance: Regulations require that breathalyzer equipment be
calibrated every six months by an accredited laboratory and that maintenance records be
kept. In this case, it was noted that the equipment was not calibrated by an accredited lab as required, raising doubt about its accuracy.
Expert Evidence
Scientific Basis: Breath alcohol testing instruments have been developed since the 1950s and rely on principles such as Henry's Law. These devices are designed to measure blood alcohol concentration (BAC) indirectly through breath samples.
Operational Standards: Officers administering breathalyzer tests are required to undergo specific training. They must adhere strictly to operational guidelines to ensure that results are reliable and admissible in Court. The Alcotest is designed to take one successful breath sample and perform two tests to ensure accuracy, while also detecting any interfering substances.
Detection of Interfering Substances: The Alcotest is equipped to detect substances that could potentially affect the results. However, its effectiveness is dependent on proper calibration and maintenance. In the Hendricks case, it was found that the equipment's calibration did not meet the regulatory standards, which compromised the reliability of the test results.
Judgment
The court's findings in this case highlight several critical issues:
Dentures and Mouth Alcohol: The accused's use of dentures was not investigated, which could have contributed to a false positive result due to the presence of mouth alcohol as the paste used to secure dentures in the mouth contain alcohol.
Calibration and Operational Failures: The failure to calibrate the Alcotest as required and to follow proper operational procedures undermined the test's reliability. The absence of a second breath sample further compromised the ability to verify the accuracy of the test.
Outcome: Ultimately, the state was unable to prove beyond a reasonable doubt that the accused was driving under the influence as charged. Consequently, the accused was acquitted of the offence.
Conclusion
The Hendricks case underscores the importance of rigorous standards and procedures in ensuring the reliability of breathalyzer tests. It reveals potential pitfalls in the use of such evidence in court and highlights the need for adherence to scientific and operational protocols to avoid wrongful convictions.
For individuals facing similar charges, understanding these nuances can be crucial in challenging the validity of breathalyzer results and ensuring that justice is served.
Author: Ulrik Hultkrantz
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