Federal Rule of Evidence 702 was first adopted in 1975 as part of the original enactment of the Federal Rules of Evidence. Beginning in 1993 the Rule was interpreted by the U.S. Supreme Court in three landmark decisions that are now know as the “Daubert Trilogy.” The Rule requires a high level of scrutiny of scientific evidence in a “Daubert” hearing before a federal trial commences.

This Daubert standard is mandatory in all federal trial courts. And approximately 42 states have adopted the Daubert standard or a substantially similar standard for the admissibility of expert testimony in their state courts, either fully or with modifications. California state courts have not. Instead, California uses the “Fry” standard which is far more lenient. And in California experts who rely on controversial science in forming an opinion may testify, and the controversy applies for the “weight” of the evidence rather than admissibility, compared to the Daubert standard which makes controversial scientific evidence inadmissible.

Large corporate defendants who are sued in California may be entitled to remove the case to federal court under some circumstances such as diversity jurisdiction. Often, their reason for doing so it to take advantage of the mandated use of Rule 702.

This new published 9th Circuit Court of Appeals decision in Favor of Monsanto in one of its “Roundup” toxic injury cases is a clear example of why employers may move to have California state cases removed to federal courts when they meet the requirements to do so.

From 1990 to 2015, Peter Engilis, Jr. routinely hand- sprayed Roundup several times per month at each of his three homes in Florida. In 2014, he was diagnosed with a blood cancer known as chronic lymphocytic leukemia (CLL), which is a type of non-Hodgkin’s lymphoma (NHL).

In November 2019, Engilis filed a lawsuit against Roundup manufacturer Monsanto in the Middle District of Florida, invoking the court’s diversity jurisdiction and asserting claims under Florida state law that were premised on the allegation that exposure to Roundup caused him to develop CLL. The case was subsequently transferred to a multidistrict litigation proceeding in the Northern District of California, in which thousands of cancer victims have alleged that Roundup caused their NHL.

In a “toxic tort claim for physical injuries,” a plaintiff must “show that he was exposed to chemicals that could have caused the physical injuries he complains about (general causation), and that his exposure did in fact result in those injuries (specific causation).” Golden v. CH2M Hill Hanford Grp., 528 F.3d 681, 683 (9th Cir. 2008).

To demonstrate that Roundup caused Engilis’s cancer, Engilis relied on the expert opinion of board-certified oncologist Dr. Andrew Schneider. Dr. Schneider submitted an expert report offering opinions on both general causation and specific causation.

Monsanto moved to exclude Dr. Schneider’s opinion. At the hearing on the motion to exclude, Monsanto’s counsel extensively cross-examined Dr. Schneider about his basis for ruling out Engilis’s obesity as a potential cause of Engilis’s cancer. In response, Dr. Schneider sought to defend his assertion that Engilis was not obese. But after conceding that he had not examined Engilis and could not say whether Engilis was obese or not, Dr. Schneider testified that, regardless of whether Engilis was obese, he did not view obesity as a potential cause of NHL. During follow-on questioning, he stated that although some medical literature reports an association between obesity and the development of NHL, his clinical experience led him to believe that obesity does not contribute to NHL.

After the hearing, the district court issued an order excluding Dr. Schneider’s specific causation opinion. The 9th Circuit Court of Appeals affirmed in the published case of Engilis et al v Monsanto 3:19-cv-07859- VC (August 2025).

The admissibility of expert testimony is controlled by Federal Rule of Evidence 702. That Rule provides that, “before admitting expert testimony, the district court must perform a gatekeeping role to ensure that the [proffered] testimony is both relevant and reliable.” The parties parties dispute the significance of the 2023 amendment to Rule 702 and the effect of that amendment on existing precedent.

Thus the Court of Appeals reviewed the current precedent starting with the “Daubert Trilogy” which refers to three landmark U.S. Supreme Court cases that established the modern standard for admitting scientific expert testimony in federal courts. These cases clarified the admissibility of expert evidence under the Federal Rules of Evidence, particularly Rule 702, replacing the earlier Frye standard. In 2000, Rule 702 was amended for the first time to codify the holdings of the Daubert trilogy, and to resolve conflicts that had arisen within the courts about the meaning of that trilogy.

The Rule was amended again in December 2023 to expressly require a proponent of expert testimony to “clarify and emphasize” that proffered expert testimony must meet the admissibility requirements of Rule 702 by a preponderance of the evidence. Before the amendment, “many courts” had erroneously held “that the critical questions of the sufficiency of an expert’s basis, and the application of the expert’s methodology, are questions of weight and not admissibility.”

“Here, the district court properly concluded that Engilis failed to establish by a preponderance of the evidence that Dr. Schneider’s conclusion was based on sufficient facts or data.”