State v. Davis, 208 N.C. App. 26 (Nov. 16, 2010)

The trial court committed reversible error by allowing the State’s expert to use “odor analysis” as a baseline for his opinion as to the defendant’s blood-alcohol level (BAC) at the time of the accident, formed using retrograde extrapolation. When the defendant reported to the police department more than ten hours after the accident, she was met by an officer. Although the officer did not perform any tests on the defendant, he detected an odor of alcohol on her breath. The expert based his retrograde extrapolation analysis on the officer’s report of smelling alcohol on the defendant’s breath. He testified that based on “look[ing] at some papers, some texts, where the concentration of alcohol that is detectable by the human nose has been measured[,]” the lowest BAC that is detectable by odor alone is 0.02. He used this baseline for his retrograde extrapolation and opined that at the time of the accident, the defendant had a BAC of 0.18. The court noted that because odor analysis is a novel scientific theory, an unestablished technique, or a compelling new perspective on otherwise settled theories or techniques, it must be accompanied by sufficient indices of reliability. Although the expert testified that “there are published values for the concentrations of alcohol that humans . . . can detect with their nose,” he did not specify which texts provided this information, nor were those texts presented at trial. Furthermore, there was no evidence that the expert performed any independent verification of an odor analysis or that he had ever submitted his methodology for peer review. Thus, the court concluded, the method of proof lacked the required indices of reliability. The court also noted that while G.S. 20-139.1 sets out a thorough set of procedures governing chemical analyses of breath, blood, and urine, the odor analysis lacked any of the rigorous standards applied under that provision. It concluded that the expert’s retrograde extrapolation was not supported by a reliable method of proof, that the odor analysis was so unreliable that the trial court's decision was manifestly unsupported by reason, and that the trial court abused its discretion in admitting this testimony.