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How DUIs in Arizona Are Being Shaped By Daubert


By Craig Rosenstein

Craig J. Rosenstein represents clients in many aspects of criminal law, including misdemeanor and felony cases, with a focus on driving under the influence (DUI) defense. He graduated from the University of Arizona in Tucson, Arizona where he received his Bachelor of Arts degree in political science and then attended Arizona State University where he received his Juris Doctor (J.D.) degree. He has been credentialed by the National College of DUI Defense. He is licensed to practice law in Arizona, as well as in the U.S. Federal District Court in the District of Arizona. He can be reached by phone at (480) 248-7666 or you can fill out our convenient online contact form below.

In Arizona, the shift from the standard set forth in Frye v. United States, 293 F. 1013 (D.C. Cir. 1923), to that in Daubert v. Merrell Dow Pharmaceuticals, Inc., 509 U.S. 579 (1993), has had profound effects on almost every type of law in which both parties enter a courtroom. The change appears to be a nuanced difference in the standards necessary to introduce scientific evidence to the trier of fact, but the practical ramifications have been significant.

This has been particularly true in the field of Arizona DUI defense. As one can imagine, the introduction of scientific evidence in a DUI trial has a substantial effect on the results of said trial. Evidence in a DUI trial can be broken up into three basic categories: (1) the observations of the arresting officer, which are not scientific in nature; (2) the results and interpretation of the roadside testing, which are clearly scientific in nature; and, (3) the results of any chemical tests that were taken, namely the blood or breath tests. This article will focus on the latter two categories.

Most people are unfamiliar with the scientific literature behind the interpretation of the roadside testing (which typically entails the eye and balancing tests). What makes these tests susceptible to Daubert challenges is the lack of peer-reviewed scientific materials that substantiate the claims made about their efficacy. The same level of scrutiny regarding the underlying science was not previously applied when Arizona used the Frye standard. These roadside tests were created in their current form when the National Highway Traffic Safety Administration (NHTSA) contracted with a private company in Southern California to validate and standardize roadside testing. A series of experiments were done to determine the accuracy of these tests. What makes these experiments susceptible to a Daubert challenge is the methodology (or lack thereof) in the testing process. In fact, some of the experiments performed had the police officers grading themselves without supervision, and reporting their results to the people conducting the experiments. This falls so far below the standards generally accepted in the gathering of evidence that any scientific claims made from those results are almost meaningless. In the case of United States v. Horn, 185 F. Supp. 2d 530 (D. Md. 2002), the entire battery of roadside tests was successfully challenged in Maryland. In a more than 70-page opinion, mostly critical of the scientific data supporting the roadside test battery, the court limited the officers from testifying about the meaning of the tests and limited it to purely their observations. For example, the officers are now limited to testify that a person put their foot down when asked to balance on one leg, but not that it correlates to a percentage chance that the person had a BAC above the legal limit as they had previously done, and still do in Arizona.

The chemical tests, namely the blood or breath tests, have similarly been challenged in Arizona and across the country recently under Daubert. August saw two major successful challenges. In Arizona, a group of attorneys won a Daubert hearing in Maricopa Superior Court concerning the blood results of DUI defendants charged with felony DUI. The court in that case criticized the Scottsdale crime lab’s knowledge of faulty equipment being used and the mechanisms they failed to implement to correct said problems. The court determined that its obligation as a gatekeeper under Rule 702 of the Arizona Rules of Evidence precluded the admission of those results.

Similarly, there was a Daubert challenge to the Intoxilyzer 8000 evidentiary breath testing device in Ohio in August. In August, the machine was determined to be scientifically unreliable to such an extent that the court, as a gatekeeper, precluded its admission. This ruling is being examined closely in Arizona because the Intoxilyzer 8000 is the only breath testing machine whose results are admissible in Arizona courts.

As one can see, Arizona’s recent switch to Daubert is having a significant effect on the admission of scientific evidence in court. In DUI prosecutions, this switch is calling into question the ability of the state to introduce evidence that had previously been used.

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