Second Circuit Affirms Mirena MDL Court’s “Hard Look” at Plaintiffs’ Experts’ Methodology

On December 8, 2020, the Second Circuit Court of Appeals affirmed the Southern District of New York’s granting of summary judgment in favor of Bayer — and resulting closure of all cases against Bayer — in the Mirena multidistrict litigation (MDL). In re Mirena IUS Levonorgestrel-Related Prod. Liab. Litig. (No. II), No. 19-2155, 2020 WL 7214264 (2d Cir. Dec. 8, 2020).

In the MDL, the plaintiffs alleged that the Mirena Intrauterine System had caused them to develop idiopathic intracranial hypertension (IIH). The District Court elected to focus first on whether the plaintiffs had evidence sufficient to establish general causation. The District Court held a Daubert hearing that lasted three days and featured testimony by 19 general causation witnesses — 7 for the plaintiffs and 12 for Bayer. On October 24, 2018, the District Court entered a detailed 156-page opinion granting Bayer’s Daubert motion as to all of the plaintiffs’ experts and denying as moot plaintiffs’ motion to preclude Bayer’s experts. In re Mirena IUS Levonorgestrel-Related Prods. Liab. Litig., 341 F. Supp. 3d 213 (S.D.N.Y. 2018). Bayer then filed a motion for summary judgment, which the District Court granted for lack of general causation and dismissed all cases in the Mirena MDL.

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