5.6.4.1 Arizona and Federal Rules of Evidence Regarding Admissibility

• Jurisdiction: Arizona

Under both Arizona and Federal Rules of Evidence, there are two requirements that must be satisfied before a witness’s testimony will be considered “expert” by the court. First, the problem must involve questions beyond ordinary knowledge and experience. In the language of the Arizona and Federal Rules of Evidence, expert testimony will be allowed only where it “will assist the trier of fact to understand the evidence or determine a fact in issue.”^[22] The second requirement is that the expert be qualified “by knowledge, skill, experience, training or education . . . “ to speak on the particular issue.^[23]

The trial judge should not rely on labels, but must investigate the competence a particular proffered witness would bring to bear on the issues, and whether it would aid the trier of fact in reaching its decision. The expert need not have complete knowledge about the field in question, but she should be able to aid the jury in...