Arizona State Legislature v. Biden, 3:24-cv-08026

President Biden established the Baaj Nwaavjo I’tah Kukveni – Ancestral Footprints of the Grand Canyon National Monument in August 2023, designating 917,618 acres as a protected area.
The Arizona State Legislature and other Plaintiffs challenged the designation, arguing it exceeded the President's authority under the Antiquities Act and conflicted with the Arizona Wilderness Act.
Three groups—Tribal Nations, conservation organizations, and the State of Arizona with its governor—moved to intervene in the consolidated litigation as parties.
Plaintiffs opposed all motions to intervene, arguing none of the proposed intervenors had interests distinct from those already represented or adequately justified separate participation.
The United States did not oppose or support intervention by any party.
The Court analyzed intervention as of right and permissive intervention under Federal Rule of Civil Procedure 24 for each movant.

Issue	Plaintiff's Argument	Defendant's Argument	Held
Should Tribal Nations be allowed to intervene as of right?	U.S. already adequately represents their interests.	U.S. interests may diverge; unique sovereign interests.	Denied—U.S. adequately represents Tribal Nations.
Should Conservation Intervenors be allowed to intervene as of right?	U.S. already adequately represents their interests.	Distinct and potentially adversarial conservation interests.	Denied—U.S. adequately represents Conservation Intervenors.
Should State and Governor of Arizona be allowed to intervene?	State’s interests not at stake, only Legislature’s.	State has distinct trustee/sovereign interests not represented.	Granted—State and Governor have right to intervene.
Should permissive intervention be granted to denied parties?	Not necessary; interests already represented.	No prejudice/delay; would assist efficient resolution.	Denied—may reapply if U.S. changes position.

W. Watersheds Project v. Haaland, 22 F.4th 828 (9th Cir. 2022) (sets out factors for intervention as of right under Rule 24(a)).
Oakland Bulk & Oversized Terminal, LLC v. City of Oakland, 960 F.3d 603 (9th Cir. 2020) (interprets Rule 24(a) intervention standards).
Citizens for Balanced Use v. Mont. Wilderness Ass’n, 647 F.3d 893 (9th Cir. 2011) (applies intervention requirements to conservation groups).
Perry v. Proposition 8 Official Proponents, 587 F.3d 947 (9th Cir. 2009) (failure to meet any Rule 24(a) element is fatal).
Sw. Ctr. for Biological Diversity v. Berg, 268 F.3d 810 (9th Cir. 2001) (practical impairment standard for intervention).
California ex rel. Lockyer v. United States, 450 F.3d 436 (9th Cir. 2006) (disposition likely affects intervenor’s interests).
Makah Indian Tribe v. Verity, 910 F.2d 555 (9th Cir. 1990) (U.S. presumed to represent tribe unless a conflict exists).
Arakaki v. Cayetano, 324 F.3d 1078 (9th Cir. 2003) (presumption of adequacy of governmental representation).
Alto v. Black, 738 F.3d 1111 (9th Cir. 2013) (presumption of adequate representation by the U.S. in tribal litigation is strong).