On June 8, 2007, the Texas Supreme Court issued a significant decision in Borg-Warner Corp. v. Flores,[i] a case that addresses what a plaintiff must show to establish that a particular defendant’s product was a substantial factor in causing plaintiff’s injury in a toxic tort case. Proving causation in toxic tort cases can, of course, be highly contentious. Following in the footsteps of the U.S. Supreme Court’s decision in Daubert,[ii] many federal and state courts, including prior decisions of the Texas Supreme Court, have adopted requirements that expert opinions on causation be reliable and probative.[iii]
The decision in Flores addresses one subset of the issues involving expert testimony on causation: namely, what expert evidence is required to establish that exposure to a particular defendant’s product caused a plaintiff’s injury when that plaintiff has also been exposed to products from other manufacturers. The plaintiff in Flores was a retired automobile mechanic who had repaired and replaced brakes for 35 years, using parts obtained by several manufacturers, including Borg-Warner. His use of Borg-Warner parts was limited to four years in early 1970s, when he used Borg-Warner disk brake pads in five to seven of the roughly 20 brake jobs he did each week. One of plaintiff’s experts, a pulmonologist, testified that plaintiff suffered from asbestosis.[iv] Another testified that the technical literature showed that some asbestos was released during the grinding of brake shoes and pads and the blowing out of brake drums. There was, however, no evidence relating specifically to the exposure resulting from the use of Borg-Warner’s products.
At trial, the jury found for plaintiff and awarded compensatory and punitive damages against Borg-Warner. On appeal, Borg-Warner claimed that there was insufficient evidence that exposure to its products had caused plaintiff’s injury. The intermediate appellate court rejected this argument, stating that “if there is sufficient evidence that the defendant supplied any of the asbestos to which the plaintiff was exposed, then the plaintiff has met the burden of proof.”[v] The Texas Supreme Court ruled that evidence that a defendant supplied “any” of the asbestos to which plaintiff was exposed was not sufficient. “Instead, . . . a plaintiff must prove that the defendant’s product was a substantial factor in causing the alleged harm.”[vi] This requires “[d]efendant-specific evidence relating to the approximate dose to which the plaintiff was exposed, coupled with evidence that the dose was a substantial factor in causing the asbestos-related disease . . . .”[vii]
The evidence in Flores failed to satisfy this requirement: “[W]hile some respirable fibers may be released upon grinding some brake pads, the sparse record here contains no evidence of the approximate quantum of Borg-Warner fibers to which Flores was exposed, and whether this sufficiently contributed to the aggregate dose of asbestos Flores inhaled, such that it could be considered a substantial factor in causing his asbestosis.”[viii] Evidence that Mr. Flores may have been exposed to “some” respirable fibers when grinding pads or blowing out brake housings was insufficient, because “[w]ithout more, we do not know the contents of that dust, including the approximate quantum of fibers to which Flores was exposed, and in keeping with the de minimis rule . . . required by our precedent, . . . the evidence of causation in this case was legally insufficient.”[ix]
The parameters of the Flores decision are not completely clear, and no doubt will be litigated in the Texas courts in the coming months. One issue will surely be what quantitative evidence of exposure to a defendant’s products will suffice to establish that exposure to that defendant’s products was a “substantial factor” in causing plaintiff’s disease.[x] Another issue will be how to apply the “substantial factor” requirement to claims involving asbestos-related cancers. While Flores itself was an asbestosis case, there is no good reason to conclude that its requirements only apply to asbestosis claims. Indeed, the Flores court quoted favorably from a California Supreme Court decision on establishing causation to a defendant’s product in a case involving a claim of asbestos-related lung cancer.[xi]
However these issues ultimately get resolved, Flores will have a significant impact in the litigation of toxic tort cases in Texas. As have decisions from other courts, such as the recent decision of the New York Court of Appeals in Parker v. Mobil Oil Corp.,[xii] the Texas Supreme Court has ruled that it is not enough for a plaintiff’s expert to opine that, because high concentrations of a toxic substance can cause disease, the much lower concentrations to which the plaintiff was exposed caused his injury.
That principle should be of particular help to a defendant in those cases where there is, at most, only slight exposure to its products and much greater exposure to the asbestos-containing products of other manufacturers. In asbestos litigation, minor defendants are often sued because the great majority of the major producers of asbestos products, particularly manufacturers of insulation products, are now bankrupt. In such cases, plaintiffs’ experts often testify that each and every exposure to asbestos was a cause of the plaintiff’s asbestos-related disease, with no concession being given to the fact that exposures to a particular defendant’s product were de minimis. Under Flores, that kind of expert testimony is now plainly insufficient to establish causation, and plaintiffs will need to reverse their prior position on quantification. Previously, a defendant that contributed little to a plaintiff’s cumulative exposure often offered testimony from an industrial hygienist quantifying the plaintiff’s exposure to that defendant’s product, often combined with testimony from a medical expert, to show that this exposure was not a substantial factor in causing plaintiff’s disease. Plaintiffs typically did not respond to this evidence by adducing quantitative evidence of their own; rather, they attacked the defendant’s evidence as being unreliable and emphasized testimony from plaintiff and co-workers that a product or work practice was “dusty.” Now plaintiffs will be required to develop their own quantitative evidence in such cases. One can expect defendants in Texas to challenge the admissibility of such evidence on grounds of lack of scientific reliability, as Texas defendants have challenged the reliability of other scientific expert evidence proffered by plaintiffs’ experts.[xiii]
In short, Flores will surely have a significant impact on asbestos and other toxic tort litigation in Texas. The need to satisfy its requirements may lead some plaintiffs to refrain from suing certain minor defendants or, quite possibly, to bring their suits in forums other than Texas.