In many privacy and other technology-related class actions, the question of whether consumers consent to the practice at issue is central.  In these cases, class action defendants have defeated motions for class certification by successfully arguing that consent is an individualized issue that is not susceptible to common proof.  And though class action plaintiffs may try and avoid this problem by excluding consenting individuals from their class definition, that solution can create new problems, including impermissible “fail-safe” classes—i.e., classes that cannot be defined until a case is resolved on the merits.