After BP’s offshore drilling rig Deepwater Horizon exploded in 2010 and discharged 200 million gallons of crude oil into the Gulf of Mexico, 90,000 workers assisted with the clean-up effort. Several workers who later developed chronic sinus conditions sued BP, alleging that exposure to crude oil and chemical dispersants used in the clean-up process had caused their health conditions. To support their case, the workers presented written opinions from scientists who had reviewed a body of epidemiological studies and arrived at the opinion that the inhalation of crude oil and dispersants can damage the sinuses. The court, however, excluded the expert evidence, holding that the experts had not arrived at their opinions in a methodologically reliable manner. With the expert reports excluded, the workers had no evidence of a potential causal link between exposure to crude oil and dispersants and chronic sinusitis, and so the court dismissed the cases.
The workers appealed, and Public Citizen filed an amicus brief urging the court of appeals to reverse the exclusion of the expert evidence. The brief explains that the Federal Rules of Evidence allow parties to present expert scientific opinions that are grounded in reliable methodology, leaving it to juries to accept or reject those opinions. The experts here, we explain, employed standard epidemiological practice by reviewing a range of studies that showed an association between crude oil and dispersants and sinus conditions and then evaluating the aggregate weight of these studies against the backdrop of existing scientific knowledge to arrive at their conclusions.