Environmental Alert: "Texas Supreme Court Clarifies Causation Standard in Multiple Source Toxic Tort Cases"


The Texas Supreme Court took what appears to be a middle ground in toxic tort cases involving exposure to the same substance from multiple sources. The Court rejected the “but for” standard advocated by the defendant, but also rejected the plaintiff’s argument that proof of any exposure could support a jury finding of causation. On July 11, 2014, the Court issued Bostic v. Georgia-Pacific Corporation, approving a lower court determination that Bostic had not proved causation, and that Georgia-Pacific should pay nothing.

Bostic suffered from mesothelioma, a rare cancer linked to asbestos exposure. He had sued 40 companies, claiming they were all, at least in part, responsible for his injuries. At trial, the jury found that Georgia-Pacific and one other company caused the injuries, and assessed millions in dollars in damages against Georgia-Pacific.

On appeal, Georgia-Pacific argued that Bostic presented no evidence that, but for exposure to Georgia-Pacific’s products, Bostic would not have developed mesothelioma. Bostic countered that he did not need to meet the “but for” test in this multiple source exposure case; Bostic argued that he must only show some exposure to asbestos from Georgia-Pacific.

The Texas Supreme Court held that neither position described Texas law. Rather, the Court held that, when exposure came from multiple sources, the plaintiff must prove “substantial factor causation” as to each defendant. “Substantial factor causation” requires more proof than just proof of any exposure, but does not require the plaintiff to meet a “but for” test.  The Court ruled that Bostic's evidence did not establish "substantial factor causation."

According to the Court, in order to meet the “substantial factor causation” requirement as to a specific defendant, the plaintiff must: present reasonably quantified exposure evidence (although mathematical precision is not required) as to the defendant’s product and as to the other sources; must prove that the exposure from the defendant’s product, alone, more than doubled the plaintiff’s risk of contracting the disease; and must establish that reasonable persons could regard the defendant’s product as a cause of the disease, in light of the evidence of the plaintiff’s total exposure.

The Court’s decision appears to leave a few significant remaining questions. Trial judges, experts and litigants may be unsure as to how far below “mathematical precision” evidence can be and still constitute reasonably quantified exposure evidence. They will also have doubts as to what relative levels of exposure from a specific product, compared with total exposure, will suffice. The Court mentions the possibility of exposure to one product that more than doubles the risk of disease, compared to another that increased the risk by a factor of 10,000. However, the Court does not indicate if this will or will not be adequate to support causation, only that juries or judges should be able to consider this circumstance.

Three justices dissented, arguing that Bostic’s evidence of “significant” exposures should be sufficient to support the jury’s finding, even without a more quantified exposure estimate. Another justice agreed with the majority’s ultimate ruling for Georgia-Pacific, but wrote separately because of concerns that the Court’s discussion of how epidemiological evidence can prove causation could have the practical effect of increasing the plaintiff’s burden of proof.

For the Court’s page where you can download the majority, concurring and dissenting opinions, click here.


DISCLAIMER: Because of the generality of this update, the information provided herein may not be applicable in all situations and should not be acted upon without specific legal advice based on particular situations.

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