Can epidemiological studies with acknowledged flaws still be admissible under Rule 702? Gunn Hill Dairy Properties v. Los Angeles Department of Water & Power Explained

In Gunn Hill Dairy Properties v. Los Angeles Department of Water & Power, the Utah Court of Appeals addressed the critical distinction between threshold reliability for admissibility and the ultimate weight of expert testimony under Rule 702 of the Utah Rules of Evidence.

Background and Facts

Multiple dairy farmers in Millard County filed suit against the operators of the Intermountain Power Plant, alleging that stray direct current electricity from the facility was harming their dairy herds by causing increased mortality rates and decreased milk production. The farmers’ veterinary expert, Dr. Keeter, conducted an epidemiological study and differential diagnosis to support causation opinions. The trial court held a five-day evidentiary hearing and excluded Dr. Keeter’s testimony on causation and damages, finding his methodology unreliable under Rule 702.

Key Legal Issues

The primary issue was whether the trial court properly applied the threshold reliability standard under Rule 702(b) when excluding expert testimony. The court had criticized Dr. Keeter’s epidemiological study for including affected farms in the control group, failing to perform detailed individual farm investigations, and contradicting statements in the Merck Veterinary Manual.

Court’s Analysis and Holding

The Court of Appeals reversed the exclusion of Dr. Keeter’s testimony, finding that the trial court exceeded its gatekeeping role by requiring more than threshold reliability. The court emphasized that Rule 702 requires only a “basic foundational showing of indicia of reliability,” not that the opinion be “indisputably correct.” The court noted that epidemiological studies routinely have flaws, but such defects typically affect the weight of evidence rather than admissibility. As the court explained, “most studies have flaws” and “objections to the inadequacies of a study are more appropriately considered an objection going to the weight of the evidence rather than its admissibility.”

Practice Implications

This decision clarifies that Utah courts must maintain the distinction between the preliminary reliability determination for admissibility and the ultimate factfinder’s evaluation of evidentiary weight. The ruling reinforces that methodological imperfections in expert studies do not automatically render testimony inadmissible if the underlying approach meets threshold reliability standards. For practitioners, this emphasizes the importance of focusing admissibility challenges on fundamental methodological unreliability rather than study limitations that can be addressed through cross-examination.