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Ruffin v. BP Exploration & Production, Inc.

Floyd Ruffin was among the thousands of workers who participated in clean-up efforts after BP’s offshore drilling rig, Deepwater Horizon, exploded in 2010 and discharged millions of gallons of oil into the Gulf of Mexico. Mr. Ruffin subsequently developed prostate cancer and then sued BP, alleging that his exposure to crude oil during the clean-up caused his condition. The district court granted summary judgment to BP, holding in relevant part that there was insufficient evidence that exposure to crude oil can cause prostate cancer. Although an expert epidemiologist had testified to a causal link between certain chemicals contained in crude oil and an increased risk of prostate cancer, the district court excluded that expert testimony as unreliable because (1) the expert did not identify precisely what level of exposure is harmful and (2) the expert relied mainly on studies involving workers in industries other than the oil industry. Mr. Ruffin appealed to the Fifth Circuit.

Public Citizen filed an amicus brief on appeal, urging the Fifth Circuit to reverse the exclusion of the expert evidence. The brief explains that Mr. Ruffin’s expert employed standard epidemiological practice by reviewing a range of studies that showed an association between the chemicals at issue and prostate cancer and then evaluating the aggregate weight of these studies against the backdrop of existing scientific knowledge to arrive at an inference that the association was likely causal. Nothing in epidemiological practice or the relevant precedent, we explain, requires an expert to identify a “harmful dose” in order to produce a reliable opinion on causation. And the brief emphasizes that it is for a jury, not the court, to determine whether the expert’s methodology and testimony are ultimately persuasive.