A little while ago Allison posted on the Third Circuit's recent decision in Carrera v. Bayer, explaining that
the court ... held that, if the defendant does not have purchase records, a consumer class action cannot be certified based on sworn customer affidavits. The court stated the "rigorous analysis" requirement for class certification "appl[ies] to the question of ascertainability," which the court called an "essential prerequisite of a class action." (Where is ascertainability found in Rule 23? It is not.) Defense-side lawyers have been rightly touting the decision as a huge win (see here and here, for example), and an article in Law 360 noted that the Third Circuit has adopted [an] “Unheard-Of Consumer Class Action Hurdle.”
On Friday, the plaintiff filed a petition for rehearing en banc. Worth reading.