To embed, copy and paste the code into your website or blog: Over the past several years, the U.S. Court of Appeals for the 9th Circuit appeared poised to sanction a generous approach to certifying proposed classes under Rule 23 of the Federal Rules of Civil Procedure. 1 Recently, however, the 9th Circuit has taken steps to tighten up the rigor of the required analysis that district courts must conduct when evaluating motions for class certification. 2 The 9th Circuit appears to have taken another step in that direction in Olean Wholesale Grocery Cooperative, Inc. v. Bumble Bee Foods LLC. 3 In Bumble Bee Foods, the 9th Circuit sharpened the standards governing Fed. R. Civ. P. 23(b)(3)’s predominance requirement, which mandates that common issues predominate over individual issues. Specifically, the Court provided much-needed teeth to the district courts’ obligations to resolve factual and legal disputes bearing on predominance—including conflicting expert testimony—before certifying a class and, for the first time, held that a proposed class containing more than a