Causation cannot be established by mere guess or conjecture; it must be established by evidence of probative value. As a result, causation is difficult to prove (especially in environmental lawsuits) and can oftentimes support a motion for summary judgment. In order to fully understand this defense, it is best to review how courts have analyzed this issue in the past. In Cerny v. Marathon Oil Corp., several homeowners asserted claims against an oilfield operator alleging that toxic emissions from its operations near their homes caused their health problems. Defendants argued that the plaintiffs’ claims fell outside a lay person’s general knowledge and experience and therefore required expert testimony which meets the requirements under Merrell Dow Pharms v. Havner. The plaintiffs disputed that the Havner standard applied, because they disclaimed recovery for any “personal injury damages” and instead only sought recovery for nuisance “symptoms typical of discomfort rather than disease.” The San Antonio Court disagreed and held that the Havner standard still applied.
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In doing so, the court rejected the application of the “strong, logical, traceable connection” test applied by the Texas Supreme Court in Morgan v. Compugraphic Corp. In that case, the court framed the causation analysis as to whether the evidence established a sequence of events that provided a strong, logically traceable connection between the plaintiff’s on-the-job accident and his injuries sufficient to support a causation finding between his accident and his injuries that: (1) are within the common knowledge and experience of laypersons; (2) did not exist before the accident; (3) appeared after and close in time to the accident; and (4) are within the common knowledge and experience of laypersons caused by the kind of accident the plaintiff suffered.
The Cerny court distinguished the Morgan case because in that case the plaintiff was previously healthy and provided testimony showing a “strong, logically traceable connection” and temporal link between the event and condition which did not previously exist. However, all three Cernys admittedly suffered from a wide range of physical and emotional conditions before the defendants commenced their oilfield operations. Further, the temporal proximity between the event and the condition that existed in the Morgan case was also absent. Accordingly, the San Antonio court held that the facts alleged by the Cernys did not fall within the Morgan exception.
Instead, the San Antonio Court held that the plaintiff’s claims concerning the alleged emissions and migration of hazardous air contaminants from nearby oil and gas operations required application of the Havner strict causation standards. To raise a fact issue under Havner, the plaintiff must show: (1) evidence of a doubling of the risk through epidemiological studies; and (2) the plaintiff is similar to the subjects in those studies.
Proof is required that the plaintiff was exposed to the same substance as in the studies, that the plaintiff’s exposure or dose level was comparable to or greater than those in the studies, that the plaintiff’s exposure occurred before the onset of injury, and that the timing of the onset of the plaintiff’s injury was consistent with that experience by those in the study. It should be noted that the dissent in Cerny claimed that it was within the common knowledge and experience for the jury to determine if excessive noise, foul odors, dust pollution, and abnormal traffic interfered with the use and enjoyment of the plaintiff’s property and would have reversed with respect to that claim.
In Martinez v. City of San Antonio, neighborhood residents brought various claims against the city alleging lead contamination from dust disseminated during excavation and construction of a sports stadium on a former iron foundry site. The court held that an expert’s opinion regarding lead disseminated in dust during excavation and construction lacked reliable scientific foundation as no demonstration was made that the study regarding lead contamination from a New Mexico smelting facility, used by expert to determine “enrichment factor” for soil samples, involved comparable conditions.
In Mitchell Energy Corporation v. Bartlett, the plaintiff relied on testimony from a geochemist that specialized in “isotopic geochemistry” to establish that the contaminants in the plaintiff’s water wells came from the defendants’ oil and gas operations. The court held that the geochemist’s testimony provided no evidence of causation in light of the fact that the expert did not gather any evidence from other gas wells in the area or rule out other possibilities of the alleged contamination.
In FPL Farming, Ltd. v. Environmental Processing Systems, the court held that there was no evidence that the wastewater had migrated to the surface of the property or that the injection well was a danger to the drinking water. Similarly, in Hagy v. Equitable Production Co., the court granted a motion for summary judgment because there was no evidence of causation in support of the plaintiff’s negligence, trespass, and nuisance claims. In Harris v. Devon Energy Production Company, L.P., the defendants similarly moved for summary judgment claiming that the plaintiffs’ claim that their water well was contaminated was not scientifically possible. Finally, in Hearn v. BHP Billiton Petroleum (Arkansas) Inc., one defendant sought summary judgment on the basis that the plaintiff had not produced any proof of a causal relationship between the operation of the injection wells and seismic events, which the plaintiffs claimed were the source of their damages.
- Causation cannot be established by mere guess or conjecture; it must be established by evidence of probative value.
- Plaintiff’s claims concerning the alleged emissions and migration of hazardous air contaminants from nearby oil and gas operations required application of the Havner strict causation standards.
- To raise a fact issue under Havner, the plaintiff must show: (1) evidence of a doubling of the risk through epidemiological studies; and (2) the plaintiff is similar to the subjects in those studies.
- An expert must also rule out other possibilities of the alleged contamination.
 Id. (citing McClure v. Allied Stores of Tex., Inc., 608 S.W.2d 901, 903 (Tex.1980)).
 Cerny v. Marathon Oil Corp., 2015 WL 5852596, at *4 (Tex. App.—San Antonio 2015, pet. filed).
 Id. at *5.
 Id. (citing City of Laredo v. Garza, 293 S.W.3d 625, 631 (Tex. App.—San Antonio 2009, no pet.); Morgan v. Compugraphic Corp., 675 S.W.2d 729, 733 (Tex. 1984) (holding that medical testimony was not necessary where plaintiff’s lay testimony established a direct, logical sequence of events between plaintiff’s return to work and exposure to chemical fumes and her injuries from the jury could infer a causal nexus with reasonable probability)).
 Id. at *4.
 Id. at *5.
 Id. at *8 (citing Meat Producers, Inc. v. McFarland, 476 S.W.2d 406, 410 (Tex. Civ. App.—Dallas 1972, writ ref’d n.r.e.)(which held that testimony from lay witnesses about the source and severity of foul odors, and that wind carried over the odors to plaintiff’s land, was sufficient to support jury’s nuisance finding); Bowie Sewerage Co. v. Chandler, 138 S.W.2d 585, 589 (Tex. Civ. App.—Fort Worth 1940, writ dism’d) (“If offensive odors are emitted from Jones Creek and may be smelled by the persons who live on plaintiff’s farm, this may be testified to by laymen, as a matter of course….”)).
 Martinez v. City of San Antonio, 40 S.W.3d 587, 589 (Tex. App.—San Antonio 2001, pet. denied).
 Id. at 595.
 Id. at 446–47.
 FPL Farming Ltd. v. Envtl. Processing Sys., L.C., 305 S.W.3d 739, 741 (Tex. App.—Beaumont 2009), rev’d, 351 S.W.3d 306 (Tex. 2011).
 Hagy v. Equitable Production Co., No. 10-c-163 (Circuit Ct., Jackson County, W. Va., Oct. 26, 2010).
 Harris v. Devon Energy Production Company, L.P., No. 4:10-cv-00708 (E.D. Tex., Dec. 15, 2010) (Doc. 36).
 Hearn, et al. v. BHP Billiton Petroleum, (Arkansas) Inc., et al., No. 4:11-cv-0474 (E.D. Ark., May 24, 2011) (Doc. 62).