The case of talc and ovarian cancer is a difficult and close case on general causation. Although I do not believe that the plaintiffs have made their case, their causal claims do not have the usual earmarks of “junk science,” so readily visible in many other litigations, such as the Zoloft birth defects cases.
Dr. Daniel Cramer is a physician and an epidemiology. He holds the title of professor of epidemiology at the Harvard University Chan School Of Public Health, as well as a professor of obstetrics, gynecology, and reproductive biology, at the Harvard Medical School. The plaintiffs called Cramer to testify on causation issues.
Cramer could have been purely duplicative as a witness, but he was used primarily on specific causation with a big boost on general causation because of his many publications on talc and ovarian cancer (a subject generally missing from Graham Colditz’s C.V.). The planned testimony for Cramer was to try to present the causal attribution of Slemp’s tumor to talc, with the understanding that since specific implied general causation, the plaintiff would obtain corroborating testimony on general causation as well.
With respect to Slemp’s known risk factors, such as her massive obesity and heavy smoking history, Cramer attempted to quantify her ex ante risks based upon her medical chart and from using risk ratios from available epidemiologic studies. Predictably, Cramer tried to diminish these ex ante risks by a highly selective reading of Slemp’s charts, but he ably deflected cross-examination criticisms by characterizing questions as quibbles and volunteering that he was not trying to ascribe plaintiff’s ovarian cancer exclusively to talc. Similarly, Cramer attempted to present the highest ex ante risk ratio for Slemp’s talc exposure, through his characterizations of her case as involving bilateral tumors and other features. Cramer tried to diminish the risk factor of obesity by claiming that fat women use talc more and that there was “synergy” between obesity and talc use. Cramer never described the evidentiary basis for this claimed synergy, or whether it was multiplicative or something less dramatic.
Interestingly, risk ratios from groups (epidemiologic studies) were used to describe her individual risks. The defense did not actively challenge this procedure. The premise of Cramer’s approach was that if an individual patient had a previous exposure or lifestyle variable that has been causally associated with ovarian cancer, then those exposures and lifestyle variables all participating in actually causing the patient’s cancer. As noted in the summary of Graham Colditz’s testimony, this assumption by Cramer is disputed. Cramer never attempted to justify the assumption by reference to any body of scientific evidence, or text. For Mrs. Slemp, Cramer opined that talc (as well as obesity and smoking) caused her serous borderline ovarian tumors. This conclusion was driven by his assumption that if Slemp had an exposure to a known cause of ovarian cancer, then it must have played a “substantial” role in causing the cancer.
Cross-Examination
The defense vigorously challenged Cramer for having failed to discuss causation in his publications. Most of these publications were epidemiologic studies, which did not necessarily provide an opportunity for full-ranging discussions of causal conclusions. Cramer effectively parried by noting that causation is not established by a single study, and single-study reports were not an appropriate vehicle for a full review and analysis of causation. As for his reviews and opinion pieces, Cramer defended his failure to state a clear causal conclusion on grounds that he had urged warning labels for personal talc products, and that a causal conclusion was not needed to justify such a warning because even a potential risk of ovarian cancer outweighed the negligible benefit of using talc in personal hygiene.
The defense plowed on with its claim that many studies lacked statistical significance, but Cramer generally lost defense counsel in technical details. For Cramer’s estimation of Slemp’s ex ante risk ratio from talc exposure, the defense challenged Cramer’s use of a one-tailed test of significance1. Cramer offered a half-hearted defense of a one-sided test in this context, and used the questions as an opportunity to repeat how low the p-value was with respect to the general association between talc and ovarian cancer. Cramer muddied the water by claiming that this calculation was superseded by further refinement of his estimate, which took into account the bilaterality of Slemp’s tumors, which obviated his one-sided confidence interval calculation. Although the details were not entirely forthcoming, the jury would not likely have seen this exchange as anything other than a quibble. The defense’s claim that Cramer had violated the “rules of epidemiology” never got off the ground, and given that the defense never presented an epidemiologist, the claim of counsel never was grounded in actual evidence.
Counterfactual Causation
The most important cross-examination of Dr. Cramer came from both J & J’s and Imerys’ counsel on the issue of counterfactual causation. Defense counsel asked Cramer, in several different ways, whether Ms. Slemp would have avoided having ovarian cancer if she had not used talc. Cramer stridently and belligerently refused to answer the question. The trial judge showed no interest in obtaining an answer to these questions. In the last effort to obtain a response from Cramer on “but for” causation, Cramer simply refused:
“I am not going to opine on the topic because it is not the task I was charged with.”
In other words, plaintiffs’ counsel and Cramer had discussed his inability to answer the counterfactual question, and decided it was simply better not respond to the question altogether. Since Mr. Smith, plaintiffs’ counsel, did not “task” him with counterfactual causation, Cramer was not going to answer it. Cramer’s intransigence was remarkable because the counterfactual question is an important component to causal inference in epidemiologic science. See, e.g., Michael Höfler, “Causal inference based on counterfactuals,” 5 BMC Med. Research Methodology 28 (2005).
In law, as in science, the counterfactual questions put to Cramer, are essential. Conduct or a product cannot be a legal cause of harm unless that cause alone, or acting in concert with other causes, was enough to result in the injury. Although legal treatises speak of “substantial factor,” the American Law Institute (ALI) defined that phrase (outside the context of overdetermined effects) negatively to make clear that “the actor’s negligent conduct is not a substantial factor in bringing about harm to another if the harm would have been sustained even if the actor had not been negligent.” Restatement (Second) of Torts § 432 (1965).
Given the mischief generated by some courts and commentators2 with respect to “substantial factor,” the ALI abandoned the phrase altogether in its most recent Restatement of the law of torts. In the current Restatement, the ALI has emphasized that the imposition of liability require that the harm claimed is one that would not have occurred in the absence of (“but for”) the defendant’s negligent conduct. Restatement (Third) of Torts: Physical and Emotional Harm § 26 cmt. J (2010); see also June v. Union Carbide Corp., 577 F.3d 1234, 1244 (10th Cir. 2009) (no material difference between Second and Third Restatements; holding that ‘‘a defendant cannot be liable to the plaintiff unless its conduct is either (a) a but-for cause of the plaintiff’s injury or (b) a necessary component of a causal set that (probably) would have caused the injury in the absence of other causes.’’).
Dr. Cramer’s refusal to answer the key counterfactual question about talc and Ms. Slemp’s ovarian cancer points to a lawlessness, both scientific and legal, in the proceedings in St. Louis, Missouri.
1 See “FAQ: What are the differences between one-tailed and two-tailed tests?” Institute for Digital Research and Education.
2 See David A. Fischer, “Insufficient Causes,” 94 Kent. L. J. 277, 277 (2005-06) (criticizing judicial obtuseness in misinterpreting the earlier Restatement’s use of “substantial factor”).
