A recent decision by the U.S. Court of Appeals for the Seventh Circuit left in its wake a circuit split affecting the class action bar. The issue dividing the circuits is whether federal courts can permit discovery to determine diversity jurisdiction in cases removed under the Class Action Fairness Act of 2005, also known as CAFA. The Seventh Circuit says yes. The U.S. Court of Appeals for the Eleventh Circuit says no. In this article, Sidley lawyers Bruce Braun and Stephen Spector explore these developments.