Daubert Doesn’t Look Much Different from Howerton When it Comes to Retrograde Extrapolation

The court of appeals gave the green light last week for law enforcement officers to continue to testify as scientific experts in DWI cases involving retrograde extrapolation–notwithstanding the legislature’s amendment of Rule 702 to adopt the Daubert standard. The court held in State v. Turbyfill that a field technician for the Forensic Test for Alcohol Branch of DHHS (FTA), who was trained as a law enforcement officer and chemical analyst (which authorized him to conduct implied consent testing on breath testing instruments), was properly allowed to testify about a retrograde extrapolation calculation he performed using an FTA form. The technician’s inability to explain whether the rate he used to make the calculation was an “average,” a “mid-point,” or a “conservative” rate—he used all three terms to describe it—did not disqualify him as an expert since he “provided the trial court with a list of some thirty-nine articles . . . regarding blood alcohol research,” and “with North Carolina cases in which this Court upheld the use of retrograde extrapolation to establish blood alcohol content.”

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