Introduction Edit

Using opinions of an expert witness (expert opinion testimony) calls for a threefold approach:

  • Identify the issues that will require an expert opinion
  • Identify a qualified expert
  • Ensure that the qualified expert will use an admissible method.

Federal Rule of Evidence 702 requires that a testifying expert be "qualified as an expert by knowledge, skill, experience, training, or education." The threshold for qualification is low, a minimal foundation of knowledge, skill, and experience suffices.[1] When faced with a proffer of expert testimony, a district court must determine whether the testimony is both reliable and relevant.[2] The court has broad discretion in assessing both requirements.[3]

The reliability requirement ensures "that an expert, whether basing testimony on professional studies or personal experience, employs in the courtroom the same level of intellectual rigor that characterizes the practice of an expert in the relevant field."[4] The offering party must show by a preponderance of the evidence (1) that the expert is qualified to render the opinion and (2) that the opinion offered has adequate support.[5] Expert testimony is not admissible if it is speculative.[6] To satisfy the relevance requirement, the proffered expert testimony must assist the trier of fact in understanding or determining a fact in issue.[7] In assessing relevance, the court must look to the governing substantive legal standard.[8]

Two primary tests (or some variant of them) govern the admission of the opinions of experts. One is the Frye test;[9] the other is the Daubert test.[10]

Federal courts Edit

Daubert has replaced the Frye test, both in federal court and in many state courts, with a test where the trial judge determines the admissibility of expert opinion testimo­ny based on its relevance and the reliability of the underlying scientific techniques. The U.S. Supreme Court suggested that whether scientific expert opinion evidence will be helpful to the trier of fact may turn on whether: (1) the scientific technique can be — and has been — tested; (2) the technique has been subjected to peer review and publica­tion; (3) there is a known or potential rate of error; and (4) the technique has been generally accepted by the relevant scientific community.

The Court made clear in Daubert and subsequent cases that this list is neither a rigid nor an exhaustive set of requirements. Daubert is generally seen as the U.S. Supreme Court’s suggestion that trial courts act as "gatekeepers" to limit the admissibility of “junk science” and encourage the development of reliable scientific and technological forensic techniques. Recent changes to article seven of the Fed.R.Evid., which governs the admissibility of expert opinion testimony, are based on Daubert and its progeny. Kumho Tire Co., Ltd. v. Carmichael[11]extended Daubert to technical areas other than those considered strictly scientific.

Technical expert opinion testimony is admissible under Federal Rule of Evidence 702 (as amended in 2000) if “(1) the testimony is based upon sufficient facts or data, (2) the testimony is the product of reliable principles and methods, and (3) the witness had applied the princi­ples and methods reliably to the case.”

State courts Edit

Many States still use a version of the Frye test. Frye allowed scientific techniques to be admitted in court if they are generally accept­ed within the relevant scientific community. As the Court of Appeals for the District of Columbia Circuit stated in Frye, “courts will go a long way in admitting expert testimo­ny deduced from a well-recognized scientific principle or discovery, [but] the thing from which the deduction is made must be sufficiently established to have gained general acceptance in the particular field in which it belongs.”[12]

As examiners employ new software and updated versions of older software in their examination of digital media, they may face Frye or Daubert challenges to that software. As examination techniques develop and as expert witnesses deduce opinions about facts and evidence, “the thing from which the deduction is made must be sufficiently established” so as to be relevant and reliable in court.

References Edit

  1. Hangarter v. Provident Life & Accident Ins. Co., 373 F.3d 998, 1015-16 (9th Cir. 2004) (full-text); see also Thomas v. Newton Int'l Enters., 42 F.3d 1266, 1269 (9th Cir. 1994) (full-text).
  2. Daubert v. Merrell Dow Pharms., Inc., 509 U.S. 579, 589 (1993) ( “Daubert I” ) (full-text).
  3. See United States v. Alatorre, 222 F.3d 1098, 1100 (9th Cir. 2000) (full-text).
  4. Kumho Tire Co. v. Carmichael, 526 U.S. 137, 152 (1999) (full-text).
  5. Daubert I, 509 U.S. at 588-90.
  6. See General Elec. v. Joiner, 522 U.S. 136, 146 (1997) (full-text).
  7. Daubert I, 509 U.S. at 591.
  8. See Daubert v. Merrell Dow Pharms., Inc., 43 F.3d 1311, 1320 (9th Cir. 1995) ( "Daubert II") (full-text).
  9. Frye v. United States, 54 App. D.C. 46, 293 F. 1013 (1923).
  10. Daubert I, 509 U.S. 579.
  11. 526 U.S. 137 (1999).
  12. Note that under Daubert, general acceptance is only one of several factors for courts to consider.

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