Overview of forensic expert witnesses:
A forensic expert may be needed not only to consult during the preparation for trial. The defense may also find it necessary for the forensic assistant or other forensic expert to testify during the trial as an expert witness. In cases where complex scientific evidence will be part of the litigation, the use of a forensics expert witness at trial may assist defense counsel in explaining or presenting complex evidence to the court or in presenting an alternate theory of the case. RCM 703 allows defense counsel to submit a request to the court to authorize the employment of an expert witness and for the Government to pay the expert’s fees.
Before granting defense counsel’s request to permit a forensics expert to testify, the court must determine that the proposed testimony is both reliable and relevant to the case. The primary rules governing the relevance and reliability of expert witnesses are Military Rules of Evidence (MRE) 104, 401, 402, 403, 702, 703, and 704.
- MRE 104 states that trial judges decide preliminary questions concerning the qualification of expert witnesses.
- MRE 401 defines relevant evidence.
- MRE 402 states that relevant evidence is admissible.
- MRE 403 establishes the test for balancing the probative value of evidence against its prejudicial impact.
- MRE 702 has three requirements for expert testimony. 1) the testimony must be based upon sufficient facts or data; 2) the testimony must be the product of reliable principles and methods; and 3) the expert must have applied the principles and methods reliably to the facts of the case.
- MRE 703 discusses the basis for an expert’s testimony. MRE 704 establishes the scope of the testimony.
The thrust of any expert analysis, however, is the second or reliability prong of MRE 702. When determining if the proffered testimony is the product of reliable scientific principles and methods, counsel must validate the expert’s qualifications by establishing the following six factors from United States v. Houser.
The qualifications of the expert.
MRE 702 states that an expert may be qualified by his or her “knowledge, skill, experience, training, or education.” This broad parameter allows a witness to qualify as an expert under a number of different foundational bases.
In addition to meeting the legal requirements of qualifying the expert witness, there are strategic advantages of presenting to the court the credentials of the expert, such as establishing the credibility of the witness to the court. For this reason, it may be unwise to agree to the prosecution’s offer to stipulate to the expert’s qualifications. The prosecution may offer to stipulate to the qualifications of the defense’s expert in an attempt to prevent the court from hearing the expert’s credentials. To avoid this tactic by the prosecution, in declining to stipulate, advise the court that it will be able to adequately judge the credibility of the witness only if the witness’s qualifications are stated for the record.
However, whether or not defense counsel agrees to stipulate would depend on number of factors, including the strength of the expert’s qualifications.
To establish qualifications, defense counsel will ask the forensic witness questions designed to elicit details about the witness’ background.
- Schools attended and degrees received. This would include both undergraduate and graduate education, degrees received and graduation dates. It also includes the areas of study.
- Certifications, licenses and other training. The name of the organization providing the certification, license or training. The current status of the certification or license.
- Employment experience. The names of companies and organizations for which the witness worked, as well as dates of employment and positions held.
- Teaching experience. The names of the institutions and courses taught.
- Awards and honors. The name of the honor and conferring organization.
- Publications. Names of articles, publications and publication dates.
- Previous expert testimony. How many trials and whether the testimony was for the defense or prosecution.
Defense counsel should beware of and be prepared to respond to any challenges to the witness’ qualifications based on negative information in the witness’ background such as poor academic performance. Before selecting a particular expert, thoroughly investigate the expert candidate’s background.
- Confirm the expert’s academic records.
- Seek references from the expert’s prior employers.
- Review transcripts of the expert’s prior testimony.
- Speak to other attorneys who have used or opposed the expert.
- Speak to others in the expert’s field about the expert’s professional reputation.
- Read as many of the expert’s publications as you can.
- Conduct a background check for criminal record and credit history.
The subject matter of the expert testimony. Expert testimony will not be admissible unless it will assist the court.
The basis for the expert testimony. According to Rule 703, the information that the witness provides must be the type of information that other experts in the field rely on. The military court has interpreted this rule to allow three types of bases:
- Facts personally observed by the expert
- Facts posed in a hypothetical question
- Hearsay reports from third parties.
United States v. Reveles, 42 M.J. 388 (1995)
The witness’ opinion must be connected to the facts of the case for which he is a witness.
The legal relevance of the evidence. The evidence must have a connection to the defense counsel’s theory about the case. See Rule 402.
The reliability of the evidence. In determining the reliability of scientific evidence, such as forensic evidence, the judge must determine if the evidence is based on a reliable, scientific methodology. Daubert v. Merrell Dow Pharmaceuticals Inc., 509 U.S. 579 (1993) In determining reliability, the Court should consider the following factors:
- whether the theory or technique can be or has been tested
- whether the theory or technique has been subjected to peer review and publication
- the known or potential rate of error in using a particular scientific technique and the standards controlling the technique’s operation
- whether the theory or technique has been generally accepted in the scientific field.
See Rule 702.
The military judge has discretion in conducting the reliability analysis and can generally use any factor that will help determine the expert’s reliability. Kumho Tire v. Carmichael, 526 U.S. 137 (1999).
- United States v. Mullins, 69 M.J. 113 (C.A.A.F.). In a trial involving the sexual assault of a child, an expert may not testify regarding the credibility or believability of a victim, or opine as to the guilt or innocence of an accused. It was error to admit expert testimony from which the court members could infer that there was a 1 in 200 chance that the allegations of child victims of sexual assault were false; such an inference derived from expert testimony invades the province of the members to determine the credibility of witnesses; an expert inference that there was a 1 in 200 chance the victim is lying undermines the duty of the panel members to determine guilt beyond a reasonable doubt).
- That the probative value of the evidence outweighs other considerations. See Rule 403. United States v. Houser, 36 M.J. 392, 400 (C.M.A. 1993)