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The Paper | The Conference | Leading Cases

The State of Judicial Gatekeeping in Minnesota

by Daniel S. Fridman and J. Scott Janoe - Harvard Law School '99

     Expert witnesses have become fixtures in today's courts. From fiber comparisons to economic projections to psychiatric evaluations, the range of offered expertise covers the span of human knowledge. Hardly a case of any consequence goes to trial without expert testimony of some kind. With such widespread use of expert testimony comes the inevitable question: "what is the trial judge's role in overseeing the testimony of expert witnesses?" Unlike lay witnesses, whose testimony a jury can evaluate based on their own common sense and experience, expert witnesses offer conclusions based on practices and knowledge beyond the ken of the average juror. As a consequence, testimony by unpoliced expert witnesses can have a potentially prejudicial effect on jurors, who may be inclined to believe the experts solely because of their "expert status." How is the trial judge to know whether the expert is merely speculating, or whether the evidence on which the expert bases his or her conclusions is sufficient to support the conclusion? Judges certainly prevent lay witnesses from speculating and are expected to exclude the testimony of a witness offering wholly speculative evidence. Why should this mandate be any different when the witness purports to be an expert?

     If one accepts the proposition that the trial judge has a duty to exclude unreliable experts, a host of concerns inevitably follows. How is a trial judge to assess the scientific or technical adequacy of expert testimony if even a cursory understanding of the issues requires specialized training? Can anyone without such training fully understand the issues and come to a rational conclusion as to their validity? To what degree can the trial judge rely on the expert's own assertions about his or her qualifications? All of these concerns carry heavy weight for in many cases the trial judge is hardly a more qualified assessor of scientific credibility than the jury itself. In this introduction and the papers which follow it, we have laid out some possible answers to the myriad questions raised by judicial gatekeeping. This first paper attempts to establish a historical perspective on gatekeeping in Minnesota. The papers which follow it give a more generalized picture of the gatekeeping debate. Ultimately we hope that you find these materials helpful in formulating or fine tuning your own approach to science in the courts.

From Frye to Daubert: Judicial Gatekeeping in the Federal Courts
     In 1923, the D.C. Circuit announced its landmark decision regarding the admissibility of expert opinion testimony on novel scientific procedures in Frye v. United States.(1) In Frye, the defendant attempted to show his innocence by proffering the results of a lie detector test that purportedly demonstrated that he was telling the truth when he denied killing the victim. The court ruled that the evidence was inadmissible because the scientific principles upon which the procedure was based were not, "sufficiently established to have gained general acceptance in the particular field in which it belongs."(2) This so-called Frye general acceptance test remained the standard employed in both federal courts and state courts around the country for years to come.

     With the adoption of the Federal Rules of Evidence in 1975, courts, scholars and practitioners alike began to question whether Frye would survive as the sole admissibility standard for expert testimony. Under the Federal Rules, judges were seemingly afforded more discretion in making admissibility determinations. Rule 104(a) assigns judges the responsibility of making a preliminary determination on whether to allow a given expert to testify. Rule 702 goes on to guide this decision by requiring the judge to determine whether the admission of such testimony will assist the trier of fact to understand evidence or determine a fact at issue. Finally, Rule 403 suggests that the judge may exclude evidence if its likely prejudicial effect outweighs its probative value. The question was then to what degree would the arguably conservative Frye general acceptance standard survive in the wake of the presumably more liberal admissibility framework embodied in the new Federal Rules of Evidence.

     The U.S. Supreme Court endeavored to answer the question of Frye's continued viability in Daubert v. Merrell Dow Pharmaceuticals, Inc.(3) In Daubert the Court held that Rule 702 did in fact supersede the Frye standard and enumerated a new standard to instruct judges on how to act as judicial gatekeepers. This new approach consisted of a two-pronged analysis of the testimony centering on the testimony's reliability and relevance. In determining reliability the court must engage in a, "preliminary assessment of whether the reasoning or methodology underlying the testimony is scientifically valid and of whether that reasoning or methodology properly can be applied to the facts at issue."(4) In addition, when determining scientific reliability the trial judge should consider:

(1) whether the proffered knowledge can be or 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 (4) whether the theory or technique has gained general acceptance in the relevant scientific discipline.(5)
This nonexhaustive list of indicia of reliability relegated the Frye standard to one of a handful of guidelines that may be employed in ruling on admissibility. In conjunction with the newly ordained relevancy prong, the reliability criteria form a substantially more robust framework with which to analyze given scientific testimony. 

Frye / Mack: Minnesota's Dominant Standard
     Minnesota has long recognized the Frye "general acceptance" test as the proper standard for the admissibility of scientific expert testimony in the state's courts.(6) Specifically, in State v. Mack, the Minnesota Supreme Court formulated the current approach to the Frye inquiry as follows:

[u]nder the Frye rule, the results of mechanical or scientific testing are not admissible unless the testing has developed or improved to the point where experts in the field widely share the view that the results are scientifically reliable as accurate.(7)
Interestingly, the focus in Minnesota on determining whether there is wide agreement that the results are "scientifically reliable" is a slightly different inquiry than the traditional Frye general acceptance standard. Acknowledging this subtle difference in focus, the Minnesota Supreme Court in State v. Schwartz(8) indicated that, "[w]e have rephrased the Frye standard to require that experts in the field generally agree that the evidence is reliable and trustworthy." This interpretation has kept the Frye/Mack standard viable even in light of the adoption of the Minnesota Rules of Evidence in 1977.

The Minnesota Rules of Evidence - Frye Preserved
     Minnesota Rule of Evidence 702 governing admissibility of expert testimony is identical to Federal Rule 702.(9) Unlike the U.S. Supreme Court, however, the Minnesota Supreme Court has not found it necessary to eschew Frye in favor of a strictly rules based approach to admissibility:

[w]e note that our supreme court, in promulgating the Minnesota Rules of Evidence, expressly reserved the common law power to refine evidentiary standards through case law. . . . The supreme court has allowed Frye to flourish, even following promulgation of those rules.(10)
Earlier in Schwartz, the state supreme court noted that it was "[u]nconvinced . . . of the need for or the wisdom of overruling these prior [Frye] decisions" in favor of a Daubert-like relevancy / reliability approach.(11) Fearing that "[w]ithout this [the Frye] safeguard . . . an undesired element of subjectivity is possible in evidentiary rulings," the Schwartz court "reaffirm[ed] that the admissibility of novel scientific evidence is determined by the application of the Frye standard."(12) Minnesota's rejection of such a relevancy / reliability approach both presaged Daubert and foreshadowed Minnesota's future reluctance to embrace the Daubert approach to admissibility.

Daubert in Minnesota: Not Adopted but Not Repudiated
     The Minnesota Supreme Court has neither embraced nor specifically denounced Daubert. In Alt, the Court of Appeals noted that although Daubert does not by its terms apply to state court proceedings, its persuasive force may be strengthened by the fact that the Minnesota Rules of Evidence are modeled after the federal rules.(13) Similarly, the Court of Appeals in State v. Bauer refrained from ruling on whether Daubert supplanted Frye in Minnesota by noting that the state supreme court is the proper forum for determining such issues.(14) Moreover, in a case involving an admissibility challenge a mere four months after Bauer, the Minnesota Supreme Court specifically chose not to rule on the "continued validity of the Frye test in Minnesota."(15) Despite this apparent unwillingness to reject Daubert unequivocally, the Frye/Mack general acceptance approach remains the prevalent standard in Minnesota. 

Joiner and the Future of Judicial Gatekeeping
     While Minnesota has been fine tuning its approach to questions of admissibility, the U.S. Supreme Court has been fleshing out the contours of admissibility under the federal rules. Specifically, in General Electric Co. v. Joiner(16) the Court determined that the "abuse of discretion" standard is the proper standard of review for a trial court's decision to admit or exclude expert testimony. As Minnesota employs a similar abuse of discretion standard to review trial court Frye admissibility determinations, it is possible that Joiner may prove helpful in guiding state appellate courts examining such lower court decisions.(17)

     In Joiner an electrician sued the manufacturers of a coolant used in electrical transformers which he occasionally came into contact with when repairing power equipment. He alleged that although he was a smoker with a history of lung cancer in his family, his exposure to the PCBs, furans, and dioxins in the coolant "promoted" his development of small cell lung cancer.(18) The defense removed the case to federal court and moved for summary judgment based partly on the contention that, "there was no admissible scientific evidence that PCBs promoted Joiner's cancer."(19) The district court granted summary judgment on the basis that, "the testimony of Joiner's experts had failed to show that there was a link between exposure to PCBs and small cell lung cancer."(20) They further went on to conclude that the testimony of Joiner's experts did not rise above subjective belief or unsupported speculation, and therefore, should not be admitted into evidence.(21) The Court of Appeals for the Eleventh Circuit reversed the district court's holding and reasoned that, "because the Federal Rules of Evidence governing expert testimony display a preference for admissibility, we apply a particularly stringent standard of review to the trial judge's exclusion of expert testimony."(22)

     The Supreme Court reversed the Court of Appeals and noted that such a "particularly stringent" standard of review was improper in this context:

Thus, while the Federal Rules of Evidence allow district courts to admit a somewhat broader range of scientific testimony than would have been admissible under Frye, they leave in place the "gatekeeper" role of the trial judge in screening such evidence. A court of appeals applying "abuse of discretion" review to such rulings may not categorically distinguish between rulings allowing expert testimony and rulings which disallow it. We likewise reject respondent's argument that because the granting of summary judgment in this case was "outcome determinative," it should have been subject to a more searching standard of review. On a motion for summary judgment, disputed issues of fact are resolved against the moving party -- here, petitioners. But the question of admissibility of expert testimony is not such an issue of fact, and is reviewable under the abuse of discretion standard.(23)
The circuit court's "particularly stringent," pro-admission standard was indeed short lived.

     In concluding that the district court did not abuse its discretion in excluding the plaintiff's experts, the Supreme Court examined the adequacy of the expert testimony the plaintiff sought to introduce to prove causation. The plaintiff's experts relied heavily upon animal studies to establish proof of causation in humans. The Court found, however, that the plaintiff failed to establish enough of a foundation to support the admissibility of these studies:

Rather than explaining how and why the experts could have extrapolated their opinions from these seemingly far-removed animal studies, respondent chose "to proceed as if the only issue [was] whether animal studies can ever be a proper foundation for an expert's opinion." Of course, whether animal studies can ever be a proper foundation for an expert's opinion was not the issue. The issue was whether these experts' opinions were sufficiently supported by the animal studies on which they purported to rely. The studies were so dissimilar to the facts presented in this litigation that it was not an abuse of discretion for the District Court to have rejected the experts' reliance on them.(24)
Finally, the Supreme Court went on to suggest that it was not an abuse of discretion for the district court to demand a closer relationship between the epidemiological studies offered by the plaintiffs and the opinions drawn from them by the experts:
A court may conclude that there is simply too great an analytical gap between the data and the opinion proffered. See Turpin v. Merrell Dow Pharmaceuticals, Inc. 959 F.2d 1349, 1360 (CA 6), cert. denied, 506 U.S. 826, 121 L. Ed. 2d 47, 114 S. Ct. 84 (1992). That is what the District Court did here, and we hold that it did not abuse its discretion in so doing.(25)
Upholding a judge's right to exclude given expert testimony on the basis of perceived analytical gaps in the science is an unprecedented broadening of the gatekeeper role. Such a ruling at first seems to run contrary to the "liberal thrust" of the Rules of Evidence as articulated in Daubert. It is uncertain whether courts will be as deferential when judges exercise their discretion in favor of admissibility of arguably questionable scientific evidence. Whether Joiner will effect Minnesota and states like her that have chosen not to adopt Daubert also remains to be seen. 


1. 293 F. 1013 (D.C. Cir. 1923).
2. Id. at 1014.
3. 113 S. Ct. 2786 (1993).
4. Id. at 2796.
5. See id. at 2796-7.
6. See, e.g., State v. Schwartz, 447 N.W.2d 422, 424 (Minn. 1989); State v. Anderson, 379 N.W.2d 70, 79 (Minn. 1985) (graphological personality assessment); State v. Mack, 292 N.W.2d 764, 768 (Minn. 1980) (hypnotically induced testimony); State v. Kolander, 52 N.W.2d 458, 464 (Minn. 1952) (lie detector tests).
7. Mack, 292 N.W.2d at 768.
8. Schwartz, 447 N.W.2d at 424.
9. Fed. R. Evid. 702 (1998) and Minn. R. Evid. 702 (1998) are identical and read: "If scientific, technical, or other specialized knowledge will assist the trier of fact to understand the evidence or to determine a fact in issue, a witness qualified as an expert by knowledge, skill, experience, training, or education may testify thereto in the form of an opinion or otherwise."
10. State v. Alt, 504 N.W.2d 38, 46 (Minn. Ct. App. 1993).
11. Schwartz, 447 N.W.2d at 424.
12. Id.
13. See Alt, 504 N.W.2d at 45.
14. See 512 N.W.2d 112, n. 1 (Minn. Ct. App. 1994).
15. State v. Klawitter, 518 N.W.2d 577, n. 1 (Minn. 1994).
16. 118 S. Ct. 512 (1997).
17. See, e.g., Crawford v. State, 716 So. 2d 1028, 1045 (Miss. 1998) ("It is well settled that the determination of the admissibility of expert witness testimony rests within the sound discretion of the trial judge.")
18. See id. at 516.
19. Id.
20. Id.
21. See id. citing General Electric Co. v. Joiner, 865 F. Supp., 1310, 1326 (N.D. Ga. 1994).
22. General Electric Co. v. Joiner, 78 F.3d 524, 529 (11th Cir. 1996) (emphasis added).
23. Joiner, 118 S. Ct. at 517 (citations omitted)..
24. Id. at 518 (citations omitted).
25. Id. at 519. 

Page Last Modified on May 5, 1999 by Dan Fridman - Copyright 1999
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