370 P.3d 761
N.M.2016Background
- Shell operated oil and gas facilities near the Westgate subdivision in Hobbs, NM; an unlined storage pit and adjacent tank battery led to widespread hydrocarbon contamination discovered in the 1990s.
- Over 200 Westgate residents sued Shell for toxic-tort injuries, including systemic lupus erythematosus and other autoimmune disorders allegedly caused or aggravated by chronic exposure to crude-oil contaminants (pristane, phytane, benzene, mercury, etc.).
- Plaintiffs proffered epidemiologist Dr. James Dahlgren, who performed a community study comparing Westgate residents to an unexposed control community, collected environmental and blood samples, reviewed medical records, and relied on animal and human toxicology literature to support general and specific causation opinions.
- The district court excluded Dahlgren’s epidemiologic study, the animal studies, and his causation opinion (except for some discrete blood-pristane rulings Plaintiffs did not appeal), concluding the evidence did not ‘‘fit’’ the case and failed to establish general causation.
- Based on that exclusion, the court granted partial summary judgment for Shell on claims for lupus and other autoimmune disorders; the Court of Appeals affirmed. The New Mexico Supreme Court granted certiorari.
- The Supreme Court reversed: it held the lower courts applied an incorrect, overly stringent admissibility standard, and that Dahlgren’s study and the relied-upon animal studies were sufficiently probative of causation to be admitted; summary judgment was reversed and the case remanded.
Issues
| Issue | Plaintiff's Argument | Defendant's Argument | Held |
|---|---|---|---|
| Whether Dahlgren’s epidemiologic study and animal/toxicology studies were admissible to show general causation for lupus and autoimmune disorders | Dahlgren’s study, animal data, exposure measurements, and Bradford Hill–style analysis render the evidence relevant and sufficiently reliable to assist the trier of fact on general causation | Evidence was too dissimilar, speculative, and failed to bridge the analytical gap from association to causation (insufficient dose-response/extrapolation) | Admissible: district court applied an incorrect, overly rigorous standard; the studies were probative and should be presented to the jury |
| Whether a judge may exclude expert testimony based on a perceived ‘‘analytical gap’’ between data and opinion (Joiner rule) | Plaintiffs argued the judge should not exclude reliable methodology simply because causation is not conclusively proven; credibility and weight are for the jury | Shell relied on Joiner to justify excluding testimony when the connection between data and conclusion appears too great a leap | New Mexico Supreme Court rejected adoption of Joiner’s ‘‘analytical gap’’ exclusion as a freestanding basis to bar evidence; such credibility/weight questions belong to the jury |
| Role of dose-response and animal-to-human extrapolation in admissibility | Dahlgren presented dose and duration extrapolations and toxicologic literature to support inference from animal studies to humans | Shell argued animal studies lacked comparable dosing and experimental conditions to support human causation | Extrapolation and dose-response are relevant considerations but need not conclusively establish causation at admissibility stage; methodology that permits reasonable inference is admissible |
| Effect of erroneous exclusion on summary judgment | Plaintiffs: exclusion created a factual dispute making summary judgment improper | Shell: exclusion justified summary judgment for lack of causation evidence | Because admissible evidence creates genuine material factual issues, summary judgment was improper; reversed and remanded |
Key Cases Cited
- Daubert v. Merrell Dow Pharm., Inc., 509 U.S. 579 (court must assess relevance and reliability of expert scientific testimony)
- Kumho Tire Co. v. Carmichael, 526 U.S. 137 (Daubert gatekeeping extends to nonscientific expert testimony principles)
- General Elec. Co. v. Joiner, 522 U.S. 136 (trial court may exclude testimony when there is too great an analytical gap—rejected as a freestanding rule by NM Supreme Court)
- Turner v. Iowa Fire Equip. Co., 229 F.3d 1202 (early victims of novel toxic exposures should not be barred from trial for lack of extensive science)
- Best v. Lowe's Home Ctrs., Inc., 563 F.3d 171 (epidemiology is not always required to support general causation)
- Norris v. Baxter Healthcare Corp., 397 F.3d 878 (framework distinguishing general and specific causation in toxic torts)
- Ambrosini v. Labarraque, 101 F.3d 129 (courts should not conflate admissibility with weight/credibility determinations)
- Kennedy v. Collagen Corp., 161 F.3d 1226 (methodology and transparent reasoning can render causation testimony admissible despite lack of conclusive proof)
- Milward v. Acuity Specialty Prods. Grp., Inc., 639 F.3d 11 (Bradford Hill-style reasoning and inference-to-best-explanation in causation analysis)