[Reliability of forensic evidence in breath alcohol analysis]

Drinking experiments were performed by using a device-combination appreciated by the German National Institut of Health (BGA) as being evidential and proposed as prototype for the future practice of breath-alcohol analysis. Comparing the breath- (BrAC) and blood alcohol-concentrations (BAC), however, there were relevant deviations. Our evaluation of the facts published Schoknecht demonstrated nevertheless distinct divergences in comparison to the blood alcohol determination: A BAC-nominal of 1% gave divergences of the nominal up to 0.25% resulted from the measured BrAC-values of Schoknecht on corresponding conversion. The divergences are distinctly above those that are tolerated by legislation according to previous standards for the blood alcohol determination. Consequently it requires further checking in standardized experiments and field experiments in order to be able to judge the practice usefulness; furthermore such further checking would have to be implemented by unconcerned institutions. Basing on these experiments an evidential breath-alcohol analysis for forensic purposes has not been established yet.