Earlier this week, the Tenth Circuit held that the citizenship of a master limited partnership for diversity jurisdiction purposes is that of all its unitholders, explaining that the Supreme Court’s decision in Carden v. Arkoma Associates, 494 U.S. 185 (1990) dictates that result.
The rules of complete diversity are technical and unforgiving. Make sure you understand how they work in any case involving newfangled partnerships and entities.
The opinion is Grynberg v. Kinder Morgan Energy Partners, L.P., written by Judge Matheson.
UPDATE (November 7, 2015): I came across this report that the ABA House of Delegates is urging Congress to amend the diversity statute so that unincorporated business entities would have the citizenship of their state of organization and the state where their principal place of business is located, like incorporated entities.