Combating drunken driving: Questioning the validity of blood alcohol concentration analysis

Abstract

The reliability and accuracy of blood alcohol concentration (BAC) results presented in South African courts of law in respect of possible driving under the influence (DUI) cases, have in recent years been subjected to intense scrutiny and severe criticism.  Research has shown that multiple factors may negatively impact on the reliability of results obtained from the analysis of such samples - including inappropriate or non-standardised sample management after acquisition thereof.  In particular, long delays between sample acquisition and the analysis thereof may compromise the validity of results.  Such delays may also negatively affect the outcome of both criminal and civil legal proceedings in possible DUI cases.  A retrospective descriptive study was conducted on records from the Pretoria Forensic Chemistry Laboratory (PFCL) regarding the relevant dates pertaining to blood samples from deceased persons which were received for analysis. These parameters included the date of sample acquisition at medico-legal mortuaries, delays in submission of samples to the laboratory and date of actual analysis.  In addition, the expiration dates of sample collection kits were recorded.  Our results show that numerous expired kits were utilised and that there was an average delay of approximately five months between sample acquisition and laboratory analysis thereof.  This delay period varied greatly but appears to correlate with geographical distance of the medico-legal mortuary from the PFCL.  In order to optimise and facilitate the administration of justice in both criminal and civil cases of alleged DUI, these shortcomings should be urgently addressed.  It is argued that the implementation of prescribed measures and standard operating procedures in sample management, together with other interventions such as accreditation of laboratories and improved resourcing of medico-legal and toxicology laboratories, is urgently required.