On April 4, 2012, in Alltell Communications, LLC v. DeJordy, the United States Court of Appeals for the Eighth Circuit held that a third-party subpoena in private civil litigation is a "suit" for purposes of an Indian tribe's common law sovereign immunity, thus requiring waiver or congressional abrogation of that immunity before compliance with the subpoena may be compelled. The court found that such third-party subpoenas "command a government unit to appear in federal court and obey whatever judicial discovery commands may be forthcoming," which could severely interfere with governmental functions. The Eighth Circuit used the U.S. Supreme Court's definition of a suit and the Supreme Court's "well-established federal ‘policy of furthering Indian self-government'" to reach its conclusion.

In Alltell, the plaintiff sued its former employee for breaching an agreement by assisting the Oglala Sioux Tribe (the "Tribe") in the Tribe's lawsuit against the plaintiff. The plaintiff served third-party subpoenas duces tecum on the Tribe and on one of the Tribe's administrators, seeking production of any documents that might establish a connection between the former employee and the Tribe's lawsuit against the plaintiff.

The Alltell decision further explicates the principle of tribal sovereign immunity, which shields Indian tribes from suit because of the general principle of common-law immunity enjoyed by sovereign powers.  The Supreme Court has previously settled the question of tribal sovereign immunity when the tribe is a party to the litigation.  In Alltell, the Eighth Circuit clarifies that the principle of tribal sovereign immunity also applies when the tribe is not a party to the litigation and the tribe is served with a subpoena for documents or testimony by a private party.