Ninth Circuit Allows Unreliably Expert Testimony To Be Presented to Jury

This is a product liability and environmental tort case arising out of findings that the City of Pomona’s (Pomona) water supply contains perchlorate above the limit established by California regulatory authorities. Pomona seeks to hold SQM North America Corporation (SQMNA) liable for costs associated with investigating and remediating perchlorate in its water supply above California state limits.

Pomona attributes the perchlorate in its water supply to local use of Chilean fertilizers containing natural perchlorate during the first half of the twentieth century, but there is no direct evidence that SQMNA’s products were used in Pomona. Pomona’s case rests on the testimony of Dr. Neil Sturchio of the University of Illinois, who testified that he applied a complex, multi-step form of “stable isotope analysis” to identify Chilean perchlorate as the dominant source of perchlorate in Pomona’s groundwater. 

SQMNA asserted that there are numerous shortcomings with respect to the validity as evidentiary proof of Pomona’s proffer: 

  1. Dr. Sturchio admitted that no other laboratory employs his approach. All of the “peer review” of Sturchio’s method cited by Pomona are papers or guides authored (or co-authored) by Dr. Sturchio or his colleagues.
  2. The Department of Defense “Guidance Manual for Forensic Analysis of Perchlorate in Groundwater using Chlorine and Oxygen Isotopic Analyses,” (DoD Manual), relied on by Pomona as “official” peer review and validation of Dr. Sturchio’s methodology was co-authored by Dr. Sturchio. The Manual acknowledges that Dr. Sturchio’s method is “provisional,” still under development, and has not been verified by independent testing by other laboratories.
  3. Dr. Sturchio’s published reference database includes only a few samples from comparison sources of synthetic perchlorate and of natural perchlorate from Chile, Texas, and Death Valley; it contains no sources from Pomona.
  4. Dr. Sturchio provided no evidence regarding error rates associated with using such a limited database to identify the sources of perchlorate in Pomona’s water supply. 

SQMNA moved to exclude Dr. Sturchio’s testimony as unreliable under Rule 702. After holding a Daubert hearing, at which Dr. Sturchio testified, the District Court concluded that: (1) Dr. Sturchio’s techniques are not yet generally accepted in the scientific community, as evidenced by the provisional language used in the DoD Manual; (2) his procedures “have not been tested by other laboratories and are not subject to retesting given the failure to take dual samples”; and (3) his reference database is “too limited” to support his conclusions about the origin of perchlorate in Pomona’s water “with an acceptable rate of error.” The District Court excluded Dr. Sturchio’s testimony.

The Ninth Circuit reversed, holding that the District Court abused its discretion in excluding Dr. Sturchio’s testimony. The Circuit panel held that SQMNA’s reliability challenges to Dr. Sturchio’s method were for the jury to decide. That court held that “only a faulty methodology or theory, as opposed to imperfect execution of laboratory techniques, is a valid basis to exclude expert testimony.” The Ninth Circuit panel further held that the sufficiency of Dr. Sturchio’s reference database was a question for the jury because the parties’ experts disagreed on that issue.


Issue Areas:

Sound Science

Read the Amicus Brief:
Question(s) Presented:

Whether a district court may exclude expert testimony as unreliable only when it is based on a “faulty methodology or theory” or whether any step of the analysis that is unreliable renders the expert’s testimony inadmissible.

Additional Background:

The Ninth Circuit panel acknowledged an apparent circuit split. It recognized that the rule it articulated conflicts with the Third Circuit’s frequently cited holding in In re Paoli R.R. Yard PCB Litig., 35 F.3d 717 (3d Cir. 1994) (Paoli II), that “any step that renders the analysis unreliable under the Daubert factors renders the expert’s testimony inadmissible[,] . . . whether the step completely changes a reliable methodology or merely misapplies that methodology.” Id. at 745 (emphasis in original).

In Daubert v. Merrell Dow Pharm., Inc., 509 U.S. 579 (1993), the Court charged trial judges with the responsibility of acting as gatekeepers to exclude unreliable expert testimony.

In Kumho Tire Co. v. Carmichael, 526U.S.137(1999), the Court clarified that this gatekeeper function includes determining reliability and admissibility where expert “testimony’s factual basis, data, principles, methods, or their application are called sufficiently into question,”and that “district courts must scrutinize whether the principles and methods employed by an expert have been properly applied to the facts of the case.”

FRCP 702: Testimony by Expert Witnesses

A witness who is qualified as an expert by knowledge, skill, experience, training, or education may testify in the form of an opinion or otherwise if:

(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.


ALF’s Amicus Brief:

In an amicus brief ALF argues that certiorari should be granted to correct the circuit court split that has resulted from many courts, including the court below, misapplying or ignoring rule 702 and this Court’s precedent on screening of expert evidence. The Ninth Circuit’s holding that only a “faulty methodology or theory” warrants exclusion of expert testimony is in direct conflict with the rule in other circuits, as the Ninth Circuit itself recognized. It also conflicts with the teachings of this Court.

The Ninth Circuit’s rule rests on a purportedly critical distinction between an expert’s principles or methodology on the one hand and “protocols” or conclusions on the other. However, this is a distinction which this Court rejected in Daubert and in Kumho Tire (trial court must determine reliability where expert “testimony’s factual basis, data, principles, methods, or their application are called sufficiently into question”) (quoting Daubert, 509 U.S. at 592). In order to protect the truth-seeking function of the judicial system, trial courts must retain the authority to exclude expert testimony where “any step” in the expert’s application of his or her chosen methodology renders the analysis itself unreliable.

The procedures of Dr. Sturchio have not undergone proper validation. First, work with collaborators (even if the collaborators are the government) is not “independent” validation; second, there is no record evidence that any of these collaborators “practiced” Dr. Sturchio’s method; and, third, this falls well short of anyone replicating Dr. Sturchio’s testing of the samples of Pomona groundwater. 

For the foregoing reasons, amici curiae urge the Court to grant the petition for a writ of certiorari.


On December 14, 2015 the Supreme Court denied certiorari.

Date Originally Posted: October 14, 2014

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