Timothy Bostic died from mesothelioma, which he alleged was caused by his exposure to asbestos from a variety of sources, including his use of asbestos-containing joint compound manufactured by Georgia-Pacific Corporation when he was a child and teenager helping his father on weekend drywall projects. He originally sued dozens of defendants and, in this case, Georgia-Pacific was the sole defendant that refused to settle, because the company argued that Bostic’s youthful incidental exposure to its products could not be proved to have caused his illness, particularly because, as a young adult, he worked at a company to which he was consistently exposed to asbestos-containing products.
Today, in Bostic v. Georgia-Pacific Corp., the Texas Supreme Court agreed with Georgia-Pacific and PLF, which filed an amicus brief in the case, by reaffirming the fundamental tort principle that liability must be based on proof of causation by a preponderance of the evidence. The court refused to ignore the importance of dose in determining a causative link and impose liability even where the plaintiff might have become ill from his exposure to background levels of asbestos or some other reason. It held that even in mesothelioma cases proof of “some exposure” or “any exposure” alone will not suffice to establish causation because if any exposure at all were sufficient to cause mesothelioma, everyone would suffer from it or at least be at risk of contracting the disease.
The court explained that a less demanding standard for causation in mesothelioma cases would impose “absolute liability against any company whose asbestos-containing product crossed paths with the plaintiff throughout his entire lifetime.” The court expressly rejected the plaintiff’s “any exposure” theory of liability: “We fail to see how the theory can, as a matter of logic, exclude higher than normal background levels as the cause of plaintiff’s disease, but accept that any exposure from an individual defendant, no matter how small, should be accepted as a cause in fact of the disease.”
The court stopped short, however, of adopting the appellate court’s requirement that the plaintiff show that “but for” his exposure to Georgia-Pacific’s products, he would not have contracted mesothelioma. While recognizing that “but for” causation is the recognized standard of proof for causation-in-fact in products liability cases, the court held that due to the nature of asbestos-related diseases that manifest over the course of many decades, a “substantial factor” analysis is the appropriate basic standard of causation. The court feared that a “but for” standard would render it impossible for a plaintiff to establish causation. The “substantial factor” test “subsumes the ‘but for’ test while reaching beyond it to satisfactorily address other situations,” such as toxic tort cases where the plaintiff suffered exposure from multiple sources.
The court further defined a “substantial factor” as one that more than doubles the risk of injury to the plaintiff. A more than doubling of the risk must be shown through reliable expert testimony based on reliable epidemiological studies. The plaintiff need not track down every possible source of asbestos exposure and disprove that those exposures caused the disease. But, if there is evidence of exposure from other defendants or sources, then a plaintiff’s proof that a a particular defendant’s product more than doubled his risk of injury may not suffice to establish substantial factor causation because “a defendant’s trivial contribution to multiple causes will not result in liability.” For example, if one defendant’s product more than doubled the plaintiff’s chance of contracting a disease, but another source of asbestos increased his chances of illness by a factor of 10,000, then the defendant’s product was not a substantial factor in causing the disease.
Because the plaintiff in this case relied on the discredited “any exposure” theory of causation, and submitted no evidence as to the dose of asbestos attributable to Georgia-Pacific, the court held that the plaintiff failed to prove that Georgia-Pacific caused Bostic’s illness and therefore, the company is not liable. In so doing, the Texas Supreme Court joined others (notably, the Pennsylvania Supreme Court) in restoring traditional tort principles to asbestos cases.