1. This case presents the question of whether a class may be certified under Federal Rule of Civil Procedure 23(b)(3) as long as plaintiffs' proposed method of proving classwide injury can be deemed "colorable," "reasonable," and "well-established." This Court has long maintained that predominance under Rule 23(b)(3) is a "stringent requirement[]," American Express Co. v. Italian Colors Restaurant, 570 U.S. 228, 234 (2013), and a plaintiff's burden is "demanding," Amchem Products, Inc. v. Windsor, 521 U.S. 591, 623-624 (1997), requiring a "close look" and "rigorous analysis" from the courts, Comcast Corp. v. Behrend, 569 U.S. 27, 34-35 (2013). Accordingly, the extent to which the predominance analysis overlaps with the merits simply "cannot be helped." Wal-Mart Stores, Inc. v. Dukes, 564 U.S. 338, 351, 363 (2011).

Because "Rule 23's requirements must be interpreted in keeping with Article III constraints," Amchem, 521 U.S. at 612-613, that "rigorous analysis" requires courts to find that plaintiffs' model "establish[es] that damages are susceptible of measurement across the entire class," Comcast, 569 U.S. at 35 (emphasis added). It would "reduce Rule 23(b)(3)'s predominance requirement to a nullity" to take the view that, "at the class-certification stage[,] any method of measurement is acceptable so long as it can be applied classwide, no matter how arbitrary the measurements may be." Id. at 36.

Whether a class action can be certified under Rule 23(b)(3) when plaintiffs' proposed method of proving classwide injury is merely 'colorable' or 'reasonable' without rigorously excluding uninjured class members