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:
Ariz. R. Evi. 702
The 2012 amendment of Ruleadopts Federal Rule of Evidence , as restyled. The amendment recognizes that trial courts should serve as gatekeepers in assuring that proposed expert testimony is reliable and thus helpful to the jury's determination of facts at issue. The amendment is not intended to supplant traditional jury determinations of credibility and the weight to be afforded otherwise admissible testimony, nor is the amendment intended to permit a challenge to the testimony of every expert, preclude the testimony of experience-based experts, or prohibit testimony based on competing methodologies within a field of expertise. The trial court's gatekeeping function is not intended to replace the adversary system. Cross-examination, presentation of contrary evidence, and careful instruction on the burden of proof are the traditional and appropriate means of attacking shaky but admissible evidence.
A trial court's ruling finding an expert's testimony reliable does not necessarily mean that contradictory expert testimony is not reliable. The amendment is broad enough to permit testimony that is the product of competing principles or methods in the same field of expertise. Where there is contradictory, but reliable, expert testimony, it is the province of the jury to determine the weight and credibility of the testimony.
This comment has been derived, in part, from the Committee Notes on Rules--2000 Amendment to Federal Rule of Evidence.
Federal Rules of Evidence, Rule.