Must a federal court obtain the power to bind a party before her citizenship becomes relevant to diversity jurisdiction under Article III? For a long time conventional wisdom has assumed the answer is "no": Article III allows Congress to authorize diversity jurisdiction based on the citizenship of persons beyond a court's power to bind at the time jurisdiction is tested. Congress, in turn, has acted on this assumption. Key provisions of the most ambitious, and controversial, expansion of diversity jurisdiction in the last decade, the 2005 Class Action Fairness Act (CAFA), hinge diversity jurisdiction on the citizenship of persons conventionally believed beyond a court's power to bind-i.e., proposed class members in an uncertified class. Based on an examination of the original semantic meaning of the Diversity Clause, this article argues that the conventional wisdom is wrong: Article III limits diversity jurisdiction to suits in which citizens of different states are brought within a court's power to bind their interests. In the process, the article sheds new light on the original meaning of an Article III "controversy" -- in particular, on whom an Article III "controversy" subsists "between" -- and raises new doubts about CAFA's constitutionality.
Mark Moller, A New Look at the Original Meaning of the Diversity Clause, 51 Wm. & Mary L. Rev. 1113, 1196 (2009)