We previously blogged about a decision in the In re Deepwater Horizon BELO litigation – Ruffin v. BP Exploration & Production, Inc. – in which the Fifth Circuit affirmed summary judgment for defendants in an alleged chemical exposure case based solely on exclusion of the plaintiff’s expert testimony on general causation without reaching the experts’ specific causation opinions. As it turns out, in another BELO case argued before the same panel on the same day, the panel analyzed the plaintiff’s experts’ specific causation opinions and declined to reach their general causation opinions. Williams v. BP Exploration & Production, — F.4th —, 2025 WL 1904153 (5th Cir. July 10, 2025). Notwithstanding the concerns we previously expressed about the Ruffin panel’s approach to general causation in isolation from specific causation, the Ruffin and Williams decisions provide a potent couplet illustrating that general causation and specific causation are two distinct steps in the analysis. Both must be proven in order for a plaintiff to make a prima facie case.