Ruffin v. BP Expl & Prod

── Ruffin v. BP Expl & Prod ── Court: Court of Appeals for the Fifth Circuit Date: May 27, 2026 Category: Private Civil Federal Case: 23-30854 Document: 120-1 Page: 1 Date Filed: 05/27/2026 United States Court of Appeals for the Fifth Circuit ____________ United States Court of Appeals Fifth Circuit No. 23-30854 FILED May 27, 2026 ____________ Lyle W. Cayce Floyd Ruffin, Clerk Plaintiff—Appellant, versus BP Exploration & Production, Incorporated; BP America Production Company, Defendants—Appellees. ______________________________ Appeal from the United States District Court for the Eastern District of Louisiana USDC Nos. 2:20-CV-334, 2:22-CV-1006 ______________________________ Before Elrod, Chief Judge, and Higginbotham and Southwick, Circuit Judges. Jennifer Walker Elrod, Chief Judge: No member of the panel nor judge in regular active service of the court having requested that the court be polled on rehearing en banc (Fed. R. App. P. and 5th Cir. R. 35), the petition for rehearing en banc is DENIED. We withdraw our prior opinion, Ruffin v. BP Expl. & Prod., Inc., 137 F.4th 276 (5th Cir. 2025), and substitute the following. This toxic-tort case arising from the 2010 Deepwater Horizon oil spill presents the issue of what expert testimony must be introduced to establish Case: 23-30854 Document: 120-1 Page: 2 Date Filed: 05/27/2026 No. 23-30854 causation. Plaintiff–Appellant Floyd Ruffin alleges that he was exposed to crude oil while employed as a clean-up worker after the spill. He was later diagnosed with prostate cancer and sued BP. The issue is whether the expert testimony that Ruffin submitted to prove that his alleged exposure caused his cancer was sufficiently “relevant” and “reliable” to be admissible under Federal Rule of Evidence 702 and Daubert v. Merrell Dow Pharmaceuticals, Inc., 509 U.S. 579 (1993). BP says it was not, arguing for a rule that would require an expert to testify to the specific quantitative amount or “dose” of chemical exposure that would cause the plaintiff’s injury. We decline to adopt such a rule because it conflicts with our precedent. But because we agree with the district court that Ruffin’s expert testimony nevertheless suffers from fatal analytical flaws, we AFFIRM the district court’s exclusion of the testimony and its associated award of summary judgment to BP. I Ruffin worked as a shoreline clean-up worker in Louisiana for five months following the 2010 Deepwater Horizon oil spill. Five years later, he was diagnosed with prostate cancer. Ruffin sued BP in the Eastern District of Louisiana pursuant to the Deepwater Horizon medical-benefits class action settlement as a “Back-End Litigation Option” (BELO) claim for alleged injuries that manifest after the date of the settlement. Ruffin claimed that he was exposed to harmful chemicals that caused his cancer while working on the clean-up effort. After discovery, Ruffin designated several experts. At issue here is Ruffin’s causation expert, Dr. Benjamin Rybicki, who is a genetic and molecular epidemiologist. Rybicki reported that Ruffin was exposed to “polycyclic aromatic hydrocarbons” (PAHs)—chemical compounds that are “ubiquitous in the environment” and occur “in coal, peat, crude oil, and shale oils”—and that at least one of these compounds can cause prostate