Reinforcing the requirement for expert testimony to support toxic tort personal injury claims under Texas law, a Texas appellate court held that claims for damages due to “symptoms caused by discomfort” do not fall within the domain of a layperson’s knowledge and experience, and therefore must be supported by expert testimony. See Cerny v. Marathon Oil Corp., No. 04-14-00650-CV, 2015 WL 5852596 (Tex. App. Oct. 7, 2015).

In 2010, Plaintiffs leased mineral rights to Marathon Oil Corp., which subsequently conducted oil and gas operations in the area surrounding Plaintiffs’ home.  After a few years of operations, Plaintiffs alleged Marathon’s oil and gas activities exposed them to noxious odors and chemicals, dust, noise, and constant traffic.  Plaintiffs claimed this worsened their pre-existing mental and physical ailments and caused property damage.  Plaintiffs sued Marathon for damages based on claims of nuisance and negligence.

Texas law requires that any plaintiff seeking relief for personal injuries caused by exposure to or migration of a toxic substance must proffer expert testimony to prove causation.  In an attempt to avoid this requirement, Plaintiffs disclaimed damages for “a diagnosed disease,” instead claiming damages for “symptoms caused by discomfort rather than disease.”  Plaintiffs asserted that the causal link between symptoms of discomfort and Marathon’s operations fell within the domain of a layperson’s knowledge and therefore causation could be proved using general common law standards of nuisance and negligence. 

In affirming the trial court’s decision to grant Defendants’ motion for summary judgment, the appellate court found that Plaintiffs had generated a false distinction between “symptoms of discomfort” and “symptoms of disease.”  The Court held that because symptoms of both discomfort and disease fall outside a layperson’s general knowledge and experience, causation of such symptoms must be proven by expert testimony.