Washington state does not use the Daubert approach to determine admissibility of expert opinion testimony. State v. Copeland, 130 Wash. 2d. 244, 259, 922 P. 2d 1304 (1996). Washington follows the Frye standard expressed in Frye v. United States, 54 App. D.C. 46, 293 F. 1013 (1923). See Copeland, 130 Wash.2d at 259, 922 P.2d at 1314.

Under Frye, Washington courts evaluate two factors: (1) whether the underlying theory is generally accepted in the scientific community, and (2) whether there are techniques, experiments or studies utilizing the theory which are capable of producing reliable results. Anderson v. Akzo Nobel Coatings, Inc., 172 Wash. 2d 593, 260 P.3d 857 (2011).

“The relevant scientific community must generally accept both ‘the underlying theory’ and the ‘techniques, experiments, or studies’ applying that theory. … The techniques, experiments, or studies must be ‘capable of producing reliable results.’ … The scientific community does not have to be unanimous; the court should exclude the expert’s opinion only ‘[i]f there is a significant dispute among qualified scientists.’ … ‘[T]he application of accepted techniques to reach novel conclusions does not raise Frye concerns.’… ‘Frye does not require every deduction drawn from generally accepted theories to be generally accepted.’ … ‘Other evidentiary requirements provide additional protections from deductions that are mere speculation.’” L.M. by & through Dussault v. Hamilton, 193 Wash. 2d 113, 128–29, 436 P.3d 803, 811 (2019) (internal citations omitted).