The Light Just Turned Yellow for Retrograde Extrapolation

I wrote in September 2015 that the court of appeals’ view of the admissibility of retrograde extrapolation under Daubert did not look much different from its take on the admissibility of that evidence under old Rule 702.  As of yesterday, it does. The court of appeals in State v. Babich, __ N.C. App. __ (2017), changed the green light for retrograde extrapolation testimony in DWI cases to yellow. Where we were. The North Carolina Court of Appeals has, on several occasions, liberally approved the admission of retrograde extrapolation testimony. For example, the court in State v. Turbyfill, __ N.C. App. __, 776 S.E.2d 249 (2015), held that a field technician for the Forensic Tests for Alcohol branch of DHHS (FTA), who was trained as a law enforcement officer, was properly allowed to testify about a retrograde extrapolation he performed using an FTA form, notwithstanding his inability to explain the basis for his calculations. And in State v. Green, 209 N.C. App. 669 (2011), the court of appeals held that the trial court properly allowed the head of the FTA to testify regarding the defendant’s specific alcohol concentration at the time of an earlier accident based on various assumptions about how many drinks the defendant consumed before he submitted to a breath test some three hours later. In only one extreme case, when the head of the FTA testified about a retrograde extrapolation he performed based on the smell of alcohol, had the court of appeals found error in the admission of [...]