Endangered Species Law & Policy

In Conservation Council for Hawaii v. Hawaiian Electric Company, Inc. (D. Haw. Apr. 24, 2026), a federal district court in Hawai’i applied Federal Rule of Evidence 702 regarding the admissibility of expert testimony in the context of a lawsuit alleging unauthorized “take” of species protected under the Endangered Species Act (ESA). The decision reflects the effort of the trial judge to balance the gatekeeping function of the judiciary, which is intended to prevent parties from blurring the line between lay and expert testimony, and the notion that parties are entitled to present relevant information to the factfinder (whether that is the judge or a jury).

At the center of most disputes over whether a person is liable for the unauthorized take of a protected species under the ESA is causation. In this case, plaintiffs allege that Maui County’s streetlights “take” protected seabirds by attracting and disorienting them, leading to collisions or grounding events known as “fallout.” Because the ESA defines “take” to include harm to listed species, the viability of the claim depends on whether plaintiffs could establish a causal connection between artificial lighting and actual death or injury of listed seabirds. Absent direct evidence, plaintiffs seek to rely on circumstantial evidence in the form of expert testimony to demonstrate causation.

When determining the threshold issue of whether expert testimony is admissible, the court functions as a gatekeeper. It is not the court’s job to decide at this juncture whether the expert is correct; rather, its function is to determine whether each expert’s testimony is sufficiently reliable and relevant to assist the trier of fact. While noting that the proponent of expert testimony bears the burden of establishing admissibility, the Court refers to Ninth Circuit precedent characterizing the standard as “flexible” rather than exacting.

Applying that standard, the court first found that plaintiffs’ experts were qualified under Rule 702. It stressed that the Rule encompasses a broad conception of expertise, including knowledge, skill, experience, training, or education. One of plaintiffs’ experts earned a Ph.D. in Zoology, and the focus of her doctoral research was Hawaiian seabirds. The other only possessed a B.S. but had four decades of experience as a wildlife biologist and had authored numerous peer-reviewed publications on seabirds and artificial light. Based on a review of a range of factors including education, experience, and publications as well as relevant fieldwork, the court found both experts clear the admissibility bar.

The court also found that defendant’s experts were qualified in their respective fields. One of defendant's experts earned a Ph.D. in Physics and served in technical roles for lighting companies for over 20 years. The other had an undergraduate degree in Physics and published and presented at various conferences in the fields of optics and lasers.

At the same time, the court’s application of Rule 702 was not without teeth. While it largely admitted the testimony of the County’s experts on artificial lighting and urban lightscapes, it excluded certain opinions that, in its view, exceeded the bounds of expertise or relevance. First, the court excluded portions of the testimony that were outside their expertise in physics and lighting technology, by barring the experts from opining on how seabirds perceive light or how lighting affects seabird behavior. Second, the court excluded testimony concerning roadway lighting safety. This testimony, the court explained, was outside the area in which the witness qualified as an expert and irrelevant to the issue of liability for unauthorized take under the ESA. These limitations reflect the court’s recognition that Rule 702 limits expert testimony to fields in which the expert is qualified and to topics that are relevant.

For practitioners, the case reflects a balanced application of Rule 702. Courts will generally admit expert testimony provided the declarant is qualified by knowledge, skill, experience, training, or education in the fields in which the expert is providing testimony. But they will not allow experts to venture into disciplines outside their competence or, at the liability phase, to introduce policy arguments unrelated to liability.