June 1998

Rule 404(b) and 404(c): New Definitions, New Tests and New Rules

by Hon. Crane McClennen and Hon. Robert L. Gottsfield

The Evolution of Arizona's Test

Arizona's test for the admissibility of novel scientific expert evidence traces back to a 1923 murder case. United States v. Frye2 addressed a criminal defendant's claim that he should have been allowed to present the results of his "systolic blood pressure deception test," a primitive lie-detector test. Because that test was not "sufficiently established to have gained general acceptance in the particular field in which it belongs," the court rejected defendant's claim and affirmed his murder conviction.3

Although the Frye test - requiring "general acceptance" in the relevant scientific community - was adopted in many federal and state courts,4 it was not until 1954 that the Arizona Supreme Court expressly addressed the admissibility of novel scientific expert evidence. State v. Olivas5 noted "scientific disagreement" about the validity of a blood alcohol test involved in that case. Without citing Frye, Olivas found that "a lack of unanimity" in the relevant scientific community regarding the validity of a scientific test "affects only the weight and not the admissibility of evidence" - a test inconsistent with Frye's "general acceptance" standard.6

Nearly a decade later, the Arizona Supreme Court first cited Frye - as precedent for excluding lie detector evidence but not as the standard for admissibility of novel scientific evidence. State v. Valdez rejected "absolute infallibility" as the test for scientific evidence, but added that until lie detector tests became endorsed "by a larger segment" of the relevant "branches of science," they were not generally admissible in court.7

Valdez did not squarely decide whether Arizona adopted Frye's "general acceptance" standard. That uncertainty finally was resolved in Scales v. City Court,8 a drunk driving case. Decided in 1979 - just two years after Arizona adopted its version of the Federal Rules of Evidence - Scalesrejected defendant's argument that a certain procedure was required for a breath analyzer to be reliable. In doing so, however, Scalesadopted the Frye test: "[t]o be accepted by a court as fact, a scientific principle must have gained general acceptance in the particular field in which it belongs."9

Since Scales, Arizona has applied Frye's "general acceptance" test to examine many types of novel scientific expert evidence. Arizona's appellate courts have found that computer accident analysis, blood tests and other types of evidence may be admissible under Frye.10 On the other hand, "voiceprint" evidence and hypnotically induced testimony both have been held to fail the Frye test.11

Certain evidence has been admitted in part and excluded in part under Frye. Horizontal gaze nystagmus intoxication evidence is admissible "to corroborate or attack," but not "to quantify," an accused's blood alcohol level.12 DNA evidence also has been admitted in part and excluded in part under Frye. In many respects, the DNA cases provide the most expansive analysis of Frye as applied by Arizona courts.

DNA testing is based on the generally accepted proposition that each individual has a unique genetic code.13 This unique code allows, for example, DNA samples from a crime scene to be compared with DNA samples from a suspect to determine if they match. Current DNA testing examines only a portion of an individual's genetic code, and 99.9 percent of the genetic code for any two people is the same.14 Accordingly, DNA testing focuses on the remaining 0.1 percent of the genetic code to determine (1) whether samples match and (2) the probability that any match was random.15

The Arizona Supreme Court has held the "principle and theory underlying DNA testing" passes the Frye test.16 For random match probability calculations, however, the Arizona Supreme Court first held that those calculations failed the Frye test.17 More recently, however, random match probability calculations have been found to meet Frye so long as certain limitations are imposed.18

Application of Frye by Arizona State Courts

The Purpose of the FryeInquiry

Frye is designed to prevent parties from unfairly exploiting expert testimony and to assure that expert evidence is reliable.19 Because science is often perceived as "synonymous with truth, there is a substantial risk that the jury may give undue weight to such evidence" and Frye recognizes "that judges and juries are not always in a position to assess the validity of the claims made by an expert witness before making findings of fact."20

Under Frye, the relevant scientific community determines whether evidence is the product of good science. Accordingly, Frye assures that scientific evidence will be assessed by "members of the relevant scientific field who can dispassionately study and test the new theory."21 Because "[n]ew discoveries are not immediately accepted," Frye allows courts to "determine whether new scientific principles are ready for the courtroom and, conversely, whether the courtroom is ready for new scientific principles."22 Under Frye, novel scientific evidence is excluded until such time as there is a pool of experts sufficient to evaluate such evidence. Because Frye does not ask the court to resolve scientific disputes, "the very existence of the dispute precludes admission of the testimony."23

When DoesFryeApply

The Frye test is limited to "new, novel or experimental scientific evidence" that rests on "scientific legitimacy," rather than "common knowledge" or personal opinion.24 Although not crisp, the distinction appears to be that expert evidence "`hing[ing] upon the validity or accuracy of some scientific principle'" must comply with Frye but that expert evidence merely helping the finder of fact to interpret the evidence "`will be received on a lesser showing of scientific certainty.'"25

Under Arizona Rules of Evidence 702 and 703, "experts may testify concerning their own experimentation and observation and opinions based on their own work without first showing general acceptance."26 This is because the weight of such evidence does not turn on the application of scientific principles but, rather, on the expert's credibility, interpretation and experience.27 Applying these principles, Arizona's appellate courts have found that Frye does not apply to, among other things, dog tracking evidence, bite mark evidence, footprint and shoe print evidence, because such evidence is "not bottomed on any scientific theory" or is not "new, novel or experimental scientific evidence."28

What DoesFrye Require?
Under Frye, the proponent of novel evidence "based on scientific, technical or specialized knowledge" must show (1) general acceptance of that knowledge (2) in the relevant scientific community.29 This inquiry does not turn on disagreements regarding experts' conclusions. Indeed, "there will be disputes over the conclusions reached, the competence of the respective experts and the method by which the scientific principles were applied."30 Rather, Frye looks at the principles underlying the expert's conclusions.

General Acceptance. General acceptance requires more than several experts testifying about the same thing. Even widespread use is not sufficient; a technique must be "without significant objection from the relevant scientific community" to pass Frye.31

"Frye does not ask judges to engage in a numbers game. General acceptance is determined by considering 'the quality, as well as quantity, of the evidence supporting or opposing a new scientific technique. Mere numerical majority support or opposition by persons minimally qualified to state an authoritative opinion is of little value.'"32

Acceptance by a "'substantial majority'" of the relevant scientific community is sufficient.33

General acceptance does not require a principle or procedure to be absolutely accurate. Lack of perfection in a principle or process generally goes to its weight not admissibility.34 Rather, the proponent of novel expert evidence must show that the procedure "has a sound scientific basis and is capable of producing a result that can be used, with awareness of any limitations, for scientific purposes."35

Relevant Scientific Community. The relevant scientific community will vary from case to case and may involve more than one group for different aspects of the same technology. The relevant scientific community must be individuals "other than those who have professional and personal interest in the outcome of the evaluation"36 and must be relatively disinterested and impartial experts "whose livelihood...is not intimately connected with approval of the technique."37 This independence ensures "that reliability will be assessed by those in the best position to do so: members of the relevant scientific field who can dispassionately study and test the new theory."38

Procedural Issues. The preferred method for addressing a Frye issue is a pre-trial hearing held outside of the presence of the jury. The failure to hold such a hearing outside of the jury's presence could result in a mistrial or reversible error.39 Accordingly, a party seeking to offer or challenge evidence subject to Frye should request an admissibility hearing sufficiently in advance of trial to comply with any procedural requirements and to avoid any claim of improper delay or prejudice.40

At a Frye hearing, the party offering the evidence has the burden to show that evidence is admissible. That burden can be met by offering expert testimony and scientific literature as well as legal authority.41 In considering whether the proffered evidence meets the Frye test, the court is not bound by the rules of evidence and can consider evidence inadmissible under those rules in making the determination.42

What Must be Done if Evidence Passes the Frye Test?

If evidence passes the Frye test, it still must be otherwise admissible. Such evidence must be supported by a proper foundation, i.e., a showing by a qualified expert that the "accepted technique was properly used and the results accurately measured and recorded."43 Moreover, such evidence must be relevant and otherwise admissible under Arizona Rule of Evidence 403.

Appellate Review of Frye Determinations

Arizona's appellate courts will review de novo a trial court's determination whether evidence passes the Frye test.44 In conducting that review, the appellate court will look to advancements in science made available afterthe Frye ruling by the trial court (and even after trial).45 Once evidence passes the Frye test on appeal, similar evidence in subsequent cases may be admitted (if foundational and other evidentiary hurdles are met) without repeating the Frye inquiry. Thus, a major benefit of the Frye test is that it aids in uniformity and avoids complex presentations in subsequent cases.46

Arizona's Standard Compared to the Federal Standard

In 1993, the United States Supreme Court held that the Federal Rules of Evidence displaced Frye. In Daubert v. Merrell Dow Pharmaceuticals, Inc., the Court replaced Frye's "general acceptance" test with factors to be balanced in determining whether novel scientific evidence should be admitted, including: (1) whether the evidence "can be (and has been) tested;" (2) "whether the theory or technique has been subjected to peer review and publication;" (3) "the known or potential rate of error and the existence and maintenance of standards controlling the technique's operations;" and (4) "'general acceptance' can yet have a bearing on the inquiry."47

These Daubert factors have shifted the focus away from Frye's "general acceptance" test to including an examination of the process and reliability of proffered scientific expert evidence. Although open to debate, the United States Supreme Court recently observed that the Daubert factors allow the admission of "a somewhat broader range of scientific testimony than would have been admissible under Frye."48 Moreover, and unlike under Frye, the appellate review for a Daubert decision is subject to the deferential abuse of discretion standard.49 Accordingly, when compared to Frye, Daubert highlights the trial court's role and, through the abuse of discretion standard on appeal, makes the trial court the final arbiter of most Daubert issues.

While not adopting Daubert, Arizona courts have criticized Frye50 and noted the profound limitations that would result from an inflexible application of Frye:

"New discoveries are not immediately accepted in the scientific community. Rigid application of the general acceptance test would forbid judicial use of a new discovery even though there may be direct experimental or clinical support for the principle. Furthermore, history shows that generally accepted scientific theory is not always correct."51

Strictly applied, Frye would have excluded the views of Charles Darwin when he wrote on evolution and Galileo's planetary theories when first espoused. Notwithstanding these limitations, however, the Arizona Supreme Court has found that the Arizona Rules of Evidence did not displace Frye and, to date, has not adopted Daubert.52

Although setting forth different approaches, Daubert and Frye also have some significant similarities. Daubert retains Frye's general acceptance test as a relevant factor. Similarly, as applied by Arizona's appellate courts, Frye focuses on the reliability of novel scientific expert evidence,53 which is one of Daubert's touchstones. These similarities, coupled with an acknowledged need to use some flexibility in making the Frye inquiry, suggest that Arizona courts may look to Daubert as authorizing an enhanced focus on reliability in addressing novel scientific expert evidence under Frye. Indeed, it may be that Arizona courts are applying Frye but also are incorporating a reliability component that should be - but is not always - an unstated part of Frye's "general acceptance" inquiry.54

Whether Arizona adopts Daubert in the future remains to be seen. At present, however, it appears that the reliability concerns reflected in Daubert are being addressed in the Frye standard applied by Arizona judges. Indeed, for the moment at least, the test being used by many state courts in Arizona for considering novel scientific expert evidence might be described as the "Fraubert" test.

Paul F. Eckstein and Samuel A. Thumma are directors of Brown & Bain, P.A., in Phoenix.is a partner with the law firm of Iacovino and Kayler in Scottsdale.


1. See, e.g., Marcia Angell, Science on Trial (1996); Peter A. Huber, Galileo's Revenge - Junk Science in the Courtroom (1991).
2. 293 F. 1013, 1013 (D.C. Cir. 1923).
3. 293 F. at 1014. Frye likely overstated his case by claiming "that conscious deception or falsehood, concealment of facts, or guilt of crime...raises the systolic blood pressure in a curve, which corresponds exactly to the struggle going on in the subject's mind." Id. at 1013 (emphasis added). In any event, after Frye "was convicted and sentenced to life imprisonment the real murderer confessed to the crime." State v. Valdez, 91 Ariz. 274, 277 n.4, 371 P.2d 894, 896 n.4 (1962).
4. Morris K. Udall, et al., Law of Evidence ยง 102, at 213 (3d ed. 1991).
5. 77 Ariz. 118, 119, 267 P.2d 893, 894 (1954).
6. Olivas, 77 Ariz. at 119, 267 P.2d at 894.
7. 91 Ariz. 274, 279-80, 371 P.2d 894, 898 (1962). Valdez noted, however, that a "conservative estimate" found lie detector evidence was accurate "75-80 percent" of the time and was inaccurate only 5 percent (or less) of the time and, accordingly, allowed lie detector evidence to be admitted by stipulation. Id. at 282, 371 P.2d at 900.
8. 122 Ariz. 231, 594 P.2d 97 (1979).
9. Scales, 122 Ariz. at 234-35, 594 P.2d at 100-01.
10. State v. Velasco, 165 Ariz. 480, 486-87, 799 P.2d 821, 827-28 (1990) (silica gel blood alcohol test) (4 to 1 decision); State v. Beaty, 158 Ariz. 232, 241-42, 762 P.2d 519, 528-29 (1988) (phosphoglucomutase blood test), cert. denied, 491 U.S. 910 (1989); Troutman v. Valley Nat'l Bank, 170 Ariz. 513, 518-19 & n.2, 826 P.2d 810, 815-16 & n.2 (Ct. App. 1992) (thermogram diagnostic test); State v. Baltzell, 175 Ariz. 437, 441, 857 P.2d 1291, 1295 (Ct. App. 1992) ("occupant kinematics" evidence) (alternative holding); Starr v. Campos, 134 Ariz. 254, 256-58, 655 P.2d 794, 796-98 (Ct. App. 1982) (remanding for further consideration admissibility of computer accident analysis).
11. State v. Gortarez, 141 Ariz. 254, 262-66, 686 P.2d 1224, 1232-36 (1984) (excluding "voiceprint" evidence in criminal trials); State ex rel. Collins v. Superior Court, 132 Ariz. 180, 193-211, 644 P.2d 1266, 1279-1297 (1982) (supplemental opinion) (hypnotically induced testimony) (5 different opinions), reaffirmed & clarified in State ex rel. Neely v. Sherrill, 165 Ariz. 508, 799 P.2d 849 (1990) (4 to 1 decision); State v. Mena, 128 Ariz. 226, 231-32, 624 P.2d 1274, 1279-80 (1981) (hypnotically induced testimony).
12. State v. Superior Court, 149 Ariz. 269, 280, 718 P.2d 171, 182 (1986) ("Blake") followed in State ex rel. Hamilton v. City Court, 165 Ariz. 514, 518-19, 799 P.2d 855, 859-60 (1990) and State ex rel. McDougall v. Ricke, 161 Ariz. 462, 463-65, 778 P.2d 1358, 1359-61 (Ct. App. 1989).
13. State v. Bible, 175 Ariz. 549, 576, 858 P.2d 1152, 1179 (1993), cert. denied, 511 U.S. 1046 (1994). The one exception to this proposition is that identical twins have the same genetic codes. Id. (quoting William C. Thompson & Simon Ford, DNA Testing: Debate Update, 28 Trial, Apr. 1992, at 52).
14. Bible, 175 Ariz. at 576, 858 P.2d at 1179 (quoting D.H. Kaye, The Admissibility of DNA Testing, 13 Cardozo L. Rev. 353, 354 (1991)).
15. Bible, 175 Ariz. at 576-77, 858 P.2d at 1179-80 (quoting D.H. Kaye, The Admissibility of DNA Testing, 13 Cardozo L. Rev. 353, 354 (1991)). The random match calculation attempts to quantify the probability that "the samples came from different individuals but, by pure chance, the DNA segments examined match." Bible, 175 Ariz. at 582, 858 P.2d at 1185.
16. Bible, 175 Ariz. at 590, 858 P.2d at 1193.
17. Bible, 175 Ariz. at 590, 858 P.2d at 1193 (1993) (holding that "there is no general acceptance in the relevant scientific community" for random match probability calculations); accord State v. Gallegos, 178 Ariz. 1, 13-14, 870 P.2d 1097, 1109-10, cert. denied, 513 U.S. 934 (1994); State v. Clark, 181 Ariz. 42, 43-45, 887 P.2d 572, 573-75 (Ct. App. 1994) (2 to 1 decision).
18. State v. Johnson, 186 Ariz. 329, 335, 922 P.2d 294, 300 (1996) (holding "DNA probability evidence calculated by use of the RFLP protocol and with the modi-fied ceiling method is generally accepted in the relevant scien-tific community and is therefore admissible under the Frye test").
19. Collins, 132 Ariz. at 199, 644 P.2d at 1285 (Frye "`prevent[s] the jury from being misled by unproven and ultimately unsound scientific methods'"); State v. Richards, 166 Ariz. 576, 577, 804 P.2d 109, 110 (Ct. App. 1990) ("Under Frye, the proponent of scientific evidence must show the evidence's underlying reliability.").
20. Blake, 149 Ariz. at 276, 277, 718 P.2d at 178, 179.
21. Blake, 149 Ariz. at 277, 718 P.2d at 179.
22. Bible, 175 Ariz. at 578, 858 P.2d at 1181.
23. Starr, 134 Ariz. at 257, 655 P.2d at 797.
24. State v. Varela, 178 Ariz. 319, 325, 873 P.2d 657, 663 (Ct. App. 1993); Blake, 149 Ariz. at 276, 718 P.2d at 178.
25. State v. Hummert, 188 Ariz. 119, 125, 933 P.2d 1187, 1193 (1997) (quoting cases).
26. Hummert, 188 Ariz. at 127, 933 P.2d at 1195.
27. State v. Boles, 188 Ariz. 129, 132, 933 P.2d 1197, 1200 (Ariz. 1997).
28. State v. Roscoe, 145 Ariz. 212, 219, 700 P.2d 1312, 1319 (1984) (dog tracking), cert. denied, 471 U.S. 1094 (1985); State v. Curry, 187 Ariz. 623, 629 & n.1, 931 P.2d 1133, 1139 & n.1 (Ct. App. 1996) (child sexual abuse accommodations syndrome ("CSAAS")); accord State v. Murray, 184 Ariz. 9, 29, 906 P.2d 542, 562 (1995) (footprint), cert. denied, 116 S. Ct. 2535 (1996); State v. Runningeagle, 176 Ariz. 59, 69, 859 P.2d 169, 179 (shoe print), cert. denied, 510 U.S. 1015 (1993); Richards, 166 Ariz. at 578, 804 P.2d at 111 (bite mark); Varela, 178 Ariz. at 324-26, 873 P.2d at 662-64 (CSAAS); see also Boles, 188 Ariz. at 132, 933 P.2d at 1200 (DNA); Hummert, 188 Ariz. at 127, 933 P.2d at 1195 (DNA).
29. E.g., State ex rel. Woods v. Filler, 169 Ariz. 224, 227, 818 P.2d 209, 212 (Ct. App. 1991); Gortarez, 141 Ariz. at 263, 686 P.2d at 1224.
30. Collins, 132 Ariz. at 198 n.3, 644 P.2d at 1284 n.3.
31. Starr, 134 Ariz. at 257, 655 P.2d at 797; see also Blake, 149 Ariz. at 277, 718 P.2d at 179.
32. Hummert, 188 Ariz. at 128 n.5, 933 P.2d at 1196 n.5 (Martone, J., concurring) (quoting People v. Leahy, 882 P.2d 321, 336-37 (Cal. 1994)).
33. Blake, 149 Ariz. at 279, 718 P.2d at 181 (quoting J. Richardson, Modern Scientific Evidence 164 (2d ed. 1974)).
34. Velasco, 165 Ariz. at 486, 799 P.2d at 827; Blake, 149 Ariz. at 279, 718 P.2d at 181.
35. Starr, 134 Ariz. at 257, 655 P.2d at 797.
36. Blake, 149 Ariz. at 277, 718 P.2d at 179.
37. Gortarez, 141 Ariz. at 263, 686 P.2d at 1233; Collins, 132 Ariz. at 199, 644 P.2d at 1285.
38. Blake, 149 Ariz. at 277, 718 P.2d at 179.
39. Bible, 175 Ariz. at 581, 858 P.2d at 1184.
40. Cf. State v. Harris, 152 Ariz. 150, 151-52, 730 P.2d 859, 860-61 (Ct. App. 1986) (failure to hold Frye hearing was not error because, inter alia, issue was first raised one day before trial).
41. Bible, 175 Ariz. at 584-86, 858 P.2d at 1187-89; Blake, 149 Ariz. at 278, 718 P.2d at 180; Collins, 132 Ariz. at 200, 644 P.2d at 1286; Baroldy v. Ortho Pharmaceutical Corp., 157 Ariz. 574, 581, 760 P.2d 574, 581 (Ct. App. 1988); State v. Bogan, 183 Ariz. 506, 510 & n.9, 905 P.2d 515, 519 & n.9 (Ct. App. 1995).
42. Ariz. R. Evid. 104(a).
43. State ex rel. Woods, 169 Ariz. at 227, 818 P.2d at 212; accord Johnson, 186 Ariz. at 335, 922 P.2d at 300; Bible, 175 Ariz. at 581, 858 P.2d at 1184; State ex rel. Collins v. Seidel, 142 Ariz. 587, 590, 691 P.2d 678, 681 (1984); Bogan, 183 Ariz. at 509, 905 P.2d at 518.
44. Bible, 175 Ariz. at 578, 858 P.2d at 1181; Bogan, 183 Ariz. at 509, 905 P.2d at 518.
45. Bible, 175 Ariz. at 586 n.33, 858 P.2d at 1189 n.33.
46. Bible, 175 Ariz. at 578, 858 P.2d at 1181.
47. 509 U.S. 579, 593-94 (1993). For Arizona federal decisions applying Daubert, see United States v. Scholl, 959 F. Supp. 1189, 1191-94 (D. Ariz. 1997); Diviero v. Uniroyal Goodrich Tire Co., 919 F. Supp. 1353 (D. Ariz. 1996), aff'd, 114 F.3d 851 (9th Cir. 1997); United States v. Crumby, 895 F. Supp. 1354, 1358-64 (D. Ariz. 1995).
48. General Elec. Co. v. Joiner, 118 S. Ct. 512, 517 (1997).
49. Joiner, 118 S. Ct. at 515.
50. Troutman, 170 Ariz. at 518-19 & n.2, 826 P.2d at 815-16 & n.2 (criticizing Frye as difficult to apply and proposing that "the focus should be a balancing between probativeness, materiality and reliability against the evidence's tendency to unfairly prejudice the other party"); cf. Bible, 175 Ariz. at 578-80, 858 P.2d at 1181-83 (noting "legitimate criticism of Frye" and "persuasive reasons for rejecting or modifying Frye").
51. Bible, 175 Ariz. at 578, 858 P.2d at 1181.
52. See, e.g., Johnson, 186 Ariz. at 331, 922 P.2d at 296 (noting Frye, "which has been followed without causing significant problems..., remains the rule in Arizona"); Bible, 175 Ariz. at 578-80, 858 P.2d at 1181-83 (finding Arizona Rules of Evidence did not displace Frye and refusing to reject Frye or adopt Daubert). It should be noted, however, that the Arizona Supreme Court has stated that "Daubert leaves many questions unanswered," Bible, 175 Ariz. at 580, 858 P.2d at 1183, and that "it is too early to properly evaluate" Daubert, Johnson, 186 Ariz. at 331, 922 P.2d at 296, not that Arizona will never adopt Daubert.
53. Blake, 149 Ariz. at 277, 718 P.2d at 179 quoted in Bible, 175 Ariz. at 578, 858 P.2d at 1181.
54. Cf. Logerquist v. Danforth, 188 Ariz. 16, 24 n.11, 932 P.2d 281, 289 n.11 (Ct. App. 1996) (noting that some federal courts, in applying Daubert, have found that repressed memory evidence is reliable and, accordingly, allow a party to introduce evidence regarding recovered memory).