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Daubert/Motion in Limine to exclude Retrograde Extrapolation at trial in Arizona DUI case.

Phoenix, AZ |

Good day,

Have any trial lawyers out there tried using Daubert to exclude an expert/analyst from testifying with regard to retrograde extrapolation in a DUI trial? Based on the scientific nature of the calculation and the fact that most analysts don't have the required information to conduct an accurate backwards calculation? There are several state supreme courts (TX - Mata, NM, NV and a few others) that have recently determined that without knowledge of type, size of drinks, duration, food consumption, whether the defendant is absorptive, post, etc an accurate retrograde extrapolation cannot be performed. Has this been attempted in AZ since we adopted Daubert? A local police officer said if there was injury they take multiple breath samples to establish pre or post absorption.

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Attorney answers 1


This is an issue I make on almost every Aggravated Assault or Manslaughter case when a person's eating/drinking information is unknown. Retrograde is not a widely accepted science and there are many assumptions that must be made. I have not yet made the argument under Daubert because it is so new in Arizona. However, I have made the motions under the Rules of Evidence.

Aaron Black
Criminal & DUI Defense Attorney
Law Office of Aaron M. Black, PLLC
3219 East Camelback Road #573
Phoenix, AZ 85018
Office #: 480-729-1683



Interesting. This is a *simple misdemeanor case(extreme dui, no crash or injuries) but I read that as of about a year ago Arizona adopted Daubert for all criminal cases. Here is an interesting case on the subject(page 17) . I would hope that the elements of speculation keep the BAC test out of my trial but I am not sure.