In an unusual turn of events, U.S. District Judge Cynthia Rufe recently granted defendants’ motion for summary judgment as to over 300 cases in the Zoloft MDL.[1] These cases were consolidated in 2012 and involved allegations that the antidepressant drug Zoloft causes birth defects. Having conducted substantial discovery and two rounds of Daubert hearings, the defendants filed a motion for summary judgment in all pending cases. Defendants argued that the plaintiffs failed to produce an expert who could establish general causation, and that as a result, plaintiffs could not prevail on any of their claims. The court agreed. Its decision essentially turned on plaintiffs’ failure to establish a causal link between Zoloft and the plaintiffs’ injuries. In a detailed opinion, Judge Rufe summarized the prior Daubert hearings before analyzing each category of evidence offered by the plaintiffs.

Previous Daubert Hearings

In the first round of Daubert hearings, plaintiffs offered the opinions of four expert witnesses on the issue of general causation. The court rejected the plaintiffs’ first expert, an epidemiologist, because she failed to base her opinion upon scientifically valid methodology and failed to adequately address epidemiological studies that did not support her opinion. The court determined that the plaintiffs’ remaining experts—a teratologist, a molecular developmental biologist, and an embryologist—could not testify that Zoloft caused birth defects in humans because the experts did not address the relevant epidemiological evidence. The court granted plaintiffs’ subsequent motion for leave to introduce a fifth expert witness, a biostatistics professor, as an expert on general causation with regard to cardiac defects. However, the court later excluded this expert’s report and testimony, in part because he similarly failed to adequately address all available epidemiological studies.

General Causation Evidence

Having summarized its decisions to exclude or limit plaintiffs’ experts, the court addressed whether plaintiffs were able to establish general causation without the excluded expert testimony. The court first considered the role of epidemiological evidence in establishing general causation. The court held that when epidemiological studies are inconsistent with a causation opinion, experts “must thoroughly analyze the strengths and weaknesses of the epidemiological research and explain why that body of research does not contradict or undermine their opinion.” In other words, plaintiffs could not simply ignore inconsistent evidence.

The court next addressed plaintiffs’ expert evidence submitted in opposition to the summary judgment motion. The court reiterated that its Daubert rulings remained in effect. Thus, the court would not allow plaintiffs to circumvent its previous rulings “under the guise of addressing specific causation or discussing new evidence.” Finally, the court considered plaintiffs’ non-expert evidence. This evidence included doctor and patient reports regarding adverse events that were perceived to occur after using Zoloft. The court concluded that these documents, although relevant to the generation of study hypotheses, were insufficient to create a material question of fact regarding general causation. Plaintiffs also submitted internal Pfizer documents discussing possible associations between Zoloft and birth defects and proposed changes to the Zoloft label. Again, the court found that these documents did not raise a genuine issue of material fact as to general causation.

Conclusion

In light of the preceding analysis, the court concluded that plaintiffs failed to raise a jury question as to whether Zoloft was capable of causing the birth defects at issue. Central to its decision was the court’s recognition that the MDL had been extensively litigated for more than three years. The court therefore rejected plaintiffs’ request to delay summary judgment or dismiss without prejudice. Although MDLs have been struck summarily in the past, it is a rare occurrence. This opinion highlights the opportunity for defendants to obtain a favorable judgment when plaintiffs fail to present adequate expert testimony or to account for unfavorable evidence.