From City of Colo. Springs v. Climax Molybdenum Co., 2009 U.S. App. LEXIS 25854 (10th Cir. Nov. 25, 2009):

In this water law litigation, Climax Molybdenum Company ("Climax") appeals the district court's denial of its motion to intervene in a set of consolidated cases over which the district court retained jurisdiction after first deciding them more than fifty years ago. The appeal presents an issue of first impression in this circuit: whether a proposed intervenor may establish standing, and thus federal court jurisdiction over its motion to intervene, by "piggybacking" on the standing of an existing party to a lawsuit over which the district court has retained jurisdiction but within which there is no current, active dispute among the parties.

Exercising appellate jurisdiction under 28 U.S.C. § 1291, we conclude that within litigation over which a district court has retained jurisdiction after entering a final decree, a proposed intervenor may not establish piggyback standing where the existing parties in the suit are not seeking judicial resolution of an active dispute among them. Because Climax is unable to establish either piggyback or independent standing in the cases at issue, we VACATE the district court's order and REMAND with instructions to dismiss Climax's motion for lack of jurisdiction. ***

1. What Climax must establish

"'[O]n many occasions the Supreme Court has noted that an intervenor may not have standing, but has not specifically resolved that issue, so long as another party to the litigation has sufficient standing to assert the claim at issue.'" San Juan County, Utah v. United States, 503 F.3d 1163, 1171-72 (10th Cir. 2007) (en banc).... Where a proposed intervenor has been permitted to intervene on the basis of an existing party's standing to assert the claim at issue, the Court has described the situation as "piggyback" standing. [Diamond v. Charles, 476 U.S. 54, 64 (1986).]

We have held that "parties seeking to intervene under Rule 24(a) or (b) need not establish [independent] Article III standing so long as another party with constitutional standing on the same side as the intervenor remains in the case." San Juan County, 503 F.3d at 1172.... We reasoned that such piggyback standing is permissible because "[i]n that circumstance the federal court has a Case or Controversy before it regardless of the standing of the intervenor." ... Under San Juan County, Climax thus must establish that "the federal court has a Case or Controversy before it," either because Climax has independent Article III standing or because "another party with constitutional standing on the same side" as Climax remains in the case....

2. Whether Climax may establish independent standing

***Climax's independent standing founders ... on the rock of fair traceability. A plaintiff's injury is fairly traceable to the challenged action of a defendant where there is a "causal connection between the injury and the conduct complained of" — -that is, where the injury is the result of "the challenged action of the defendant and not the result of the independent action of some third party not before the court." Lujan v. Defenders of Wildlife, 504 U.S. 555, 560 (1992).... Here, "Climax did not allege that any of the existing parties in the Consolidated Cases has performed or proposed any act that threatens Climax's water rights or their relative priorities." ... "Instead, Climax has alleged that acts or proposed acts of the Colorado State Engineer threaten its water rights." ... The State Engineer is not a party to the Consolidated Cases and is "not before the court," Lujan, 504 U.S. at 560. Any injury in fact to its ... rights that Climax may suffer, therefore, is not fairly traceable to a challenged action of any existing party to the Consolidated Cases. Climax is unable to establish independent standing to intervene.

3. Whether Climax may establish piggyback standing

To establish piggyback standing, Climax must demonstrate that there remains in the Consolidated Cases, on the same side as Climax, another party with Article III standing. In other words, there must be "another party to the litigation [that has] sufficient standing to assert the claim at issue." San Juan County, 503 F.3d at 1171 (quotation omitted).

The critical issue we must decide in this appeal is whether there remains a constitutional Case or Controversy before the federal court — and thus standing for the existing parties — where that court has retained jurisdiction over a case in which it has already issued a final decree, but where there is no current, active dispute among those existing parties that they have asked the court to resolve.... [W]e conclude that despite its "retained jurisdiction," a federal court in such a situation does not have before it a Case or Controversy, and that the existing parties consequently do not have constitutional standing upon which a prospective intervenor may piggyback. ***

We agree with the reasoning of [Dillard v. Chilton County Comm'n, 495 F.3d 1324, 1330 (11th Cir. 2007) (per curiam), cert. denied, Green v. Chilton County Comm'n, 128 S. Ct. 2961 (2008)] and [United States v. Accra Pac, Inc., 173 F.3d 630, 633 (7th Cir. 1999)]and now hold that within litigation over which a district court has retained jurisdiction after entering a final decree, a proposed intervenor may not establish piggyback standing where the existing parties are not seeking judicial resolution of an active dispute among themselves.