Ascertainability Requirement in Class Litigation: Lessons From Byrd v. Aarons and Carrera v. Bayer Corp.

Strategies for Challenging Class Membership and Defeating Certification

Recording of a 90-minute CLE webinar with Q&A

Conducted on Thursday, September 17, 2015

Recorded event now available

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Program Materials

This CLE webinar will provide class counsel with a review of Byrd v. Aaron’s Inc., Carrera v. Bayer Corp., and related court decisions addressing the ascertainability requirement for class certification. The panel will examine the scope and impact of developing case law on certification proceedings, and provide insights into how defense counsel are faring with challenging certification on grounds that the proposed class is insufficiently ascertainable.


In the wake of the Third Circuit’s class certification reversal in Carrera v. Bayer Corp., a growing number of courts have held that plaintiff classes cannot be certified without meeting the ascertainability requirement. Ascertainability requires that class membership be objectively determined at the onset of class litigation.

In April 2015, the Third Circuit issued another decision addressing ascertainability, Byrd v. Aaron’s Inc., which reaffirmed that ascertainability is a fundamental requirement for class certification. However, unlike in Carrera, the Third Circuit held that the district court applied too stringent a standard in determining that ascertainability had not been satisfied in a case involving owners and lessees of computers on which spyware had been activated.

The Third Circuit rulings create new strategic opportunities, as well as challenges, for defense counsel opposing certification. Similar opportunities and challenges have been generated by recent ascertainability rulings by other courts as well. See, e.g., Frey v. First Nat’l Bank Sw., No. 13-10375, 2015 WL 728066 (5th Cir. Feb. 20, 2015) (per curiam); DuRocher v. Nat’l Collegiate Athletic Ass’n, No. 1:13-cv-01570-SEB-DML, 2015 WL 1505675 (S.D. Ind. Mar. 31, 2015); Perrine v. Sega of Am., Inc., No. 13-cv-01962-JD, 2015 WL 2227846 (N.D. Cal. May 12, 2015); LeBlanc v. Exxon Mobil Corp., No. 14-201-SDD-RLB, 2015 WL 1221560 (M.D. La. Mar. 17, 2015); Dei Rossi v. Whirlpool Corp., No. 2:12-cv-00125-TLN-CKD, 2015 WL 1932484 (E.D. Cal. Apr. 28, 2015).

Class counsel challenging certification on ascertainability grounds must understand the elements of ascertainability and circumstances in which a class is or is not likely to be found to be ascertainable.

Listen as our authoritative panel discusses recent developments in the application of the ascertainability requirement and the anticipated impact of the latest case law trends for counsel opposing certification.



  1. Overview of ascertainability requirement in class certification
  2. Court rulings on the ascertainability requirement and impact on future class litigation
  3. Best practices for challenging class membership and defeating certification due to insufficient ascertainability


The panel will review these and other key issues:

  • Court rulings in cases involving the ascertainability requirement for class certification
  • Recent court opinions on ascertainability that may be leveraged by class counsel at the certification hearing
  • Criteria articulated by courts that make class membership too difficult to ascertain


David Kouba
David Kouba

Arnold & Porter

Mr. Kouba’s practice focuses on class action litigation and other complex commercial matters, and he has defended...  |  Read More

Rose, Nina
Nina R. Rose

Skadden Arps Slate Meagher & Flom

Ms. Rose has extensive experience defending consumer fraud and false advertising class actions and product liability...  |  Read More

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