Law - Expert Testimony, Digital Evidence Handling and Software Validation: Frye and Daubert

Frank Kardasz. June 28, 2015.  Editor: Ava Gozo.
 

The Federal Rules of Evidence, specifically Rule 702, addresses testimony by expert witnesses.  The rule states, in general, that a witness may qualify as an expert based upon knowledge, skill, experience, training, or education; and if the court qualifies a person as an expert, the witness may then testify by providing an opinion.

Frye

In conjunction with the Federal Rules of Evidence, two important court cases provide further guidance for those who handle and process digital evidence.  The 1923 case of Frye v. United States, 293 F. 1013, discussed the admissibility of the polygraph test as evidence.  The court decided that expert testimony must be based upon scientific methods that are established and accepted by a meaningful segment of the associated scientific community.  Those provisions came to be known as the Frye Standard.

Daubert

In 1993, the case of Daubert v. Merrell Dow Pharmaceuticals superseded Frye in some jurisdictions.  Daubert provided further guidelines for admitting scientific expert testimony.  Under Daubert, the trial judge is tasked with deciding whether or not scientific expert testimony is truly  based upon scientific knowledge.

One of the other important factors in the Daubert decision related to empirical testing.  The court defined scientific methodology as the process of formulating a hypothesis and conducting experiments to prove or disprove the hypothesis, and to consequently establish the validity of scientific expert testimony.

Verify

For digital forensics examiners this means that blindly using untested and unverified software or unproven techniques during examinations may lead to court challenges questioning the validity of the techniques and software.  Consequently, it behooves digital forensic examiners to validate software programs by first practicing and experimenting with programs and techniques in a testing environment.

Assuming that those validation tests prove that the techniques and software perform in a reliable, repeatable, and valid manner, then that validation might be sufficient to convince the court regarding validity.

While Frye and Daubert may not be applicable in all US States, the transient cross-jursidiction nature of cyber-evidence suggests that examiners who adhere to both Frye and Daubert would be well-equipped to defend against legal challenges attacking their work.

References

Daubert v. Merrell Dow Pharmaceuticals, 509 US 579.
Retrieved from https://supreme.justia.com/cases/federal/us/509/579/

Federal Rules of Evidence. (n.d.). Rule 702 - Testimony by expert witness. Michigan Legal Publishing Ltd.
Retrieved from https://www.rulesofevidence.org/article-vii/rule-702/

Frye v. United States, 293 F. 1013 (D.C. Cir. 1923).
Retrieved from http://www.law.ufl.edu/_pdf/faculty/little/topic8.pdf

Nordberg, P. (September 17, 2006). Resolving Daubert Challenges.
Retrieved from http://www.daubertontheweb.com/procedure.htm

Walsh, J.T. (Spring, 1998). The evolving standards of admissibility of scientific evidence. American Bar. Vol. 2, No. 1.
Retrieved from http://www.americanbar.org/newsletter/publications/gp_solo_magazine_home/gp_solo_magazine_index/walsh.html

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