Yesterday the Arizona Supreme Court issued an order amending Arizona Rule of Evidence 702 to conform almost identically to its Federal counterpart. This amendment renders the trial court a “gatekeeper” for expert witness testimony and is designed to restrict the admissibility of “junk science” and otherwise “unreliable” expert opinion testimony. The order can be found at:http://www.azcourts.gov/Portals/21/MinutesCurrent/R100035.pdf The new Arizona rule reads:

Ariz. R. Evid. 702: A witness who is qualified as an expert by knowledge, skill, experience, training, or education may testify in the form of an opinion or otherwise if:

(a) the expert's scientific, technical, or other specialized knowledge will help the trier of fact to understand the evidence or to determine a fact in issue;

(b) the testimony is based on sufficient facts or data;

(c) the testimony is the product of reliable principles and methods; and

(d) the expert has reliably applied the principles and methods to the facts of the case.

Where the Arizona and Federal rules are now nearly identical, the Commentary to the rules is not. The Commentary to the new Arizona rule is much more circumspect than its Federal counterpart. Despite this divergence, it can be expected that federal case law will be heavily relied upon by the Arizona courts in interpreting the new rule since Daubert v. Merrell DowPharmaceuticals, 509 U.S. 579 (1993) and the cases and rule that followed have been around for over 15 years.

An excellent source of information concerning the Federal rule and interpreting case law can be found at www.daubertontheweb.com. Sadly the author of this excellent site passed away in 2010 and I am uncertain to what extent his colleagues have stepped up to keep it current. It is nonetheless an excellent starting point for researching the new standard.

I also highly recommend you consult “Reference Manual on Scientific Evidence” prepared by the Federal Judicial Center to aid judges in applying the new rule. This publication can be found on line at http://www.fjc.gov/public/pdf.nsf/lookup/sciman00.pdf/$file/sciman00.pdf