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Judicial gatekeepers: the changing role of judicial officers and expert testimony
By Mark E. Windham and Eamon McMahon

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George Bernard Shaw wryly observed that "Science never solves a problem without creating ten more" - an observation made clearly evident in a judge's role in examining scientific testimony in court. Rare indeed is the trial without scientific evidence, and rarer still is the scientific theory without controversy - a problematic development when it comes to admission of scientific evidence in court.

The objective of this article and self-study test is to familiarize readers with recent California opinions dealing with the rule of bench officers in determining the admissibility of expert testimony. Readers will learn about the traditional approach in Kelly/Frye and the newer federal standard created in Daubert and Kumho Tire, as well as the new California approach established in Sargon Enterprises v. USC.


Several recent California decisions have reshaped the role of judicial officers in determining the admissibility of expert testimony, most significantly: Sargon Enterprises v. USC, 55 Cal. 4th 747 (2012), but also In Re Lockheed Litigation Cases, 115 Cal. App. 4th 558 (2004), and People v. Prince, 40 Cal. 4th 1179 (2007). This new formulation establishes the judge as a gatekeeper for information, tasked with determining what scientific evidence is allowable in court. This new formulation refocuses the standard from the long-established Kelly/Frye rule to the newer federal standard created in Kumho Tire. Especially critical is the judge's role in evaluating and ensuring that the scientific methodology is sound - a role that involves the examination of underlying scientific methodologies and logic.

The Evolution of Standards for Expert Testimony

The current California rule is founded in the federal standard, originally established in 1923 in Frye v. United States, 293 F. 1013 (D.C. Cir. 1923), and subsequently modified in the California case People v. Kelly, 17 Cal. 3d 24 (1976). These standards were predicated on historical deference to the scientific community in determining what information was admissible, based on the generally accepted methods and practices. This approach placed a premium on consensus within the scientific community, and minimized the judge's role in determining if new techniques and methodologies were to be admitted in court.

However, the subsequent modifications to the Federal Rules in Evidence rendered these decisions moot federally, and resulted in a national shift in how courts treated expert testimony as states reconsidered their own standards. The critical aspect of this shift was the elevation of the judge to a more active role in determining the admissibility of scientific techniques. The language of the 1973 Federal Rules of Evidence reformulated the guidelines for expert testimony, mandating a new approach to expert testimony, predicated on the usefulness of the expert's specialized knowledge to help determine a fact in issue, the sufficiency of the evidence used in that testimony, the reliability of the methods used to give testimony and the reliable application of such facts and methods to the matter at bar. See Fed. Rules Evid. Rule 702.

The New Federal Standard: Daubert and Kumho Tire

The shift between the old and new standards was addressed and clarified in Daubert v. Merrell Dow Pharmaceuticals, 509 U.S. 579 (1993), which expanded upon the general tenets of Rule 702 of the Federal Rules of Evidence. Under this Rule, in order to admit expert testimony, the judge must decided that all the following exist: "(a) the expert's scientific, technical, or other specialized knowledge will help the trier of fact to understand the evidence or to determine a fact in issue; (b) the testimony is based on sufficient facts or data; (c) the testimony is the product of reliable principles and methods; and (d) the expert has reliably applied the principles and methods to the facts of the case. Fed. Rules Evid. Rule 702.

The new formulation focused on several factors, but the key development was the installation of the judge as a gatekeeper for scientific evidence, which shifted away from the general deference of the Kelly/Frye rule. In this new role, judges now had to consider if the theory or technique was testable, subjected to peer review, had a demonstrable error rate, was subject to standards controlling its operation, and if it was generally accepted within the relevant scientific community. Through this set of guidelines, Daubert allowed judges significantly more ability to tailor the admissibility of the evidence to individual cases.

This principle was expanded in Kumho Tire Co. v. Carmichael, 526 U.S. 137 (1999), which applied the Daubert standard to all expert testimony. Additionally, Kumho Tire specified that the Daubert factors were not the be-all, end-all of evaluating expert testimony, but were instead intended to function as a flexible framework for analysis that allowed judges to dynamically respond to the particulars of individual cases.

California Adopts and Modifies the Federal Standard

The new California approach established in Sargon Enterprises v. USC follows this standard closely, while leaving in place People v. Leahy, 8 Cal. 4th 587 (1994). In Leahy, the state Supreme Court chose to maintain the Kelly/Frye standard for admissibility of new scientific techniques, with its deference to the scientific community. Nineteen years later Sargon vested significantly more discretion in the hands of the trial judge with regards to expert testimony. While Sargon is now operative, the Leahy standard still necessitates the application of the Kelly/Frye standard in considering novel scientific techniques. This creates an overlap of precedent; new scientific techniques are subject to the strictures of both the Leahy standard and the Sargon formulation.

Under the guidance of Leahy, courts are instructed to defer to the scientific community and apply a three-pronged test that examines the general acceptance of the theory, the witness' qualification as an expert, and whether the technique was correctly applied. After satisfying these requirements, the proffered expert testimony must also pass muster under Sargon, as all established scientific methods are still subject to the guidelines of Sargon.

Sargon draws on California Evidence Code Sections 801, 802 and 803 while still looking to the federal formulation for guidance, focusing on the factual basis of the expert testimony to determine its admissibility.

Evidence Code Section 801 permits an expert to render an opinion only if the opinion is "(a) Related to a subject that is sufficiently beyond common experience that the opinion of an expert would assist the trier of fact; and (b) Based on matter (including his special knowledge, skill, experience, training, and education) perceived by or personally known to the witness or made known to him at or before the hearing, whether or not admissible, that is of a type that reasonably may be relied upon by an expert in forming an opinion upon the subject to which his testimony relates, unless an expert is precluded by law from using such matter as a basis for his opinion."

Evidence Code Section 802 provides, in relevant part, that "A witness testifying in the form of an opinion may state on direct examination the reasons for his opinion and the matter (including, in the case of an expert, his special knowledge, skill, experience, training, and education) upon which it is based, unless he is precluded by law from using such reasons or matter as a basis for his opinion."

Under Evidence Code Section 803, "The court may, and upon objection shall, exclude testimony in the form of an opinion that is based in whole or in significant part on matter that is not a proper basis for such an opinion. In such case, the witness may, if there remains a proper basis for his opinion, then state his opinion after excluding from consideration the matter determined to be improper."

Sargon emphasizes that there must be a "reasonable basis for the particular opinion offered" and attempts to draw a line excluding expert testimony or evidence that is "based on speculation or conjecture." Additionally, judges are required to consider if the facts given actually support the conclusion the expert is drawing (General Electric Co v. Joiner, 522 U.S. 136 (1997)), and under Sargon should restrict such testimony accordingly. Under the new rule, the judge's role is to apply this flexible standard while abstaining from any value judgments about competing scientific methods. Sargon effectively brought California evidentiary standards into line with the federal standard, while retaining the older Leahy bar for new methods.

Judicial Objectives

Ultimately, the purpose of the judge's gatekeeping role in examining evidence under Sargon is "simply to exclude clearly invalid and unreliable expert opinion." Judges are strictly cautioned against weighing the merits of varying scientific methods against each other and in examining the conclusions themselves. As Daubert teaches us, it is the methodology that the judicial officer should focus upon in his or her analysis. The role of the court is not to resolve conflicts or controversies between competing scientific theories, but rather to examine if the technique presented by the expert is logical and that the conclusion is adequately supported by the information presented. It is in this light that the judicial officer should operate in the gatekeeper role to exclude only that testimony which is clearly unsupported by logic or is unreliable, based on the examination of the methodology and supporting factual basis for a given opinion.

Conflicting Application

So how exactly does the new standard work? Sargon cites as examples the appropriate application of this methodology in both civil and criminal contexts, ranging from issues of toxic torts (In re Lockheed Litigation Cases), to blood stain analysis (People v Moore, 51 Cal. 4th 386 (2011)), to the modus operandi of a serial killer (People v. Prince). The repeated application of the standard has reinforced the notion that it is the methodology - not the conclusion - that is at issue for the judge to examine.

Courts are granted wide discretion in admitting or barring certain methods, and Sargon specifies that a ruling is only an abuse of discretion if it "is so irrational or arbitrary that no reasonable person could agree with it." In this context, it is important to weigh carefully the facts and the conclusions drawn from them; correlation does not imply causation, but such logical traps can lead to admission of spurious science into the courtroom. As Sargon's newly minted scientific gatekeepers, judges must be more vigilant in separating the wheat of solid scientific theory from the chaff of speculative pseudoscience and conjecture.

Mark E. Windham is a judge in Los Angeles County Superior Court.

Eamon McMahon is a student at UCLA School of Law, class of 2015.

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