7. Unincorporated associations include organizations such as partnerships, charitable organizations, and trade unions. Under the general diversity rules, unincorporated associations are not treated as an entity but rather take on the citizenship of all of the association’s members. See Carden v. Arkoma Assocs., 494 U.S. 185, 110 S.Ct. 1015, 108 L.Ed.2d 157 (1990)(limited partnership); United Steelworkers of America v. R.H. Bouligny, Inc., 382 U.S. 145, 86 S.Ct. 272, 15 L.Ed.2d 217 (1965) (trade union). Should the citizenship of a professional corporation be analogized to that of a corporation or a partnership?

In Hoagland v. Sandberg, Phoenix & Von Gontard, P.C., 385 F.3d 737 (7th Cir. 2004), the Court of Appeals drew “a bright line between corporations and all other associations,” so that the professional corporation was treated as an entity and the citizenship of its members did not count for purposes of diversity jurisdiction. Id. at 741. Every circuit court to have addressed this question has reached the same holding. See Zambelli Fireworks Mfg. Co., Inc.

v. Wood, 592 F.3d 412, 420 (3d Cir. 2010); see also Dodge,Determining the Citizenship of LLC Members for Diversity Purposes: Seemingly Simple, Difficult Enough to Compel an Amendment to 28 U.S.C. § 1332(c)(1), 80 Tul. L. Rev. 661 (2005). How are unincorporated associations treated for diversity purposes under the Class Action Fairness Act? See 28 U.S.C. § 1332 (d)(10).