The Arizona Supreme Court will allow prosecutors to use blood test results provided by the Scottsdale Crime Lab in a series of DUI cases against Defendants who had challenged the reliability of the lab’s equipment. In rejecting the Defendants’ arguments to exclude the test results, the Court opined that questions about testing methodology or the credibility of expert testimony should be left for a jury to decide.
The Court’s ruling stems from eleven separate Defendants charged with aggravated DUI. In accordance with standard procedure, two vials of blood were collected from each Defendant during the course of their individual investigations, one of which was tested by the Scottsdale Crime Lab (SCL) to determine their blood alcohol levels. Although the Defendants never disputed the accuracy of their individual results, they argued that the testing methodology was not properly applied and that the testing instrument, known as a gas chromatograph, was not sufficiently reliable. A Superior Court agreed and precluded the State from introducing the Defendant’s test results.
The State successfully challenged the Superior Court ruling in the Arizona Court of Appeals, noting that the SCL instrument had produced 31 errors out of 21,000, none of which involved any of the Defendants who challenged the results. The State further noted that that there was never any evidence presented indicating that the results of any of the Defendants’ blood tests produced by the SCL were wrong, and that only one of the Defendants had his second blood sample independently tested but chose not to reveal the results.
In its opinion to deny the Defendant’s petition to review the Appeals Court ruling in favor of the State, the Supreme Court stated, “We hold that courts, as gatekeepers, should consider whether a methodology has been correctly applied. But we conclude that errors in application should result in the exclusion of evidence only if they render the expert’s conclusions unreliable; otherwise, the jury should be allowed to consider whether the expert properly applied the methodology in determining the weight or credibility of expert testimony.”
The ruling allows the eleven DUI cases to proceed in Superior Court.