The San Diego Superior Court erred when it disallowed Hlastala from testifying about certain issues regarding breath. Also some very interesting discussions on McNeal.
“Defendant’s appeal from the conviction is based on the trial court’s ruling disallowing any expert testimony from defendant that would have presented a physiologist’s scientific criticisms of the reliability of the data produced by breath test machines, which are based on the assumption that such devices only measure alveolar (deep lung breath) air. Defendant’s offer of proof from his expert would have provided testimony that this assumption is not always justified, and that a series of physiological factors (e.g., individual breathing patterns, body temperature, blood hematocrit, and breath temperature) may affect the transmission of alcohol in gas form, from the bloodstream to the lower and upper portions of the lungs, to the trachea and mouth and back again, thereby making such breath measurements unreliable, and undermining, in turn, the application of the standardized partition ratio calculation for converting breath levels to blood alcohol levels. (§ 23610, subd. (b).)[1][2]”