In re United States, 139 S. Ct. 452

Plaintiffs sued the United States alleging constitutional rights (substantive due process and equal protection) to certain climate conditions and seeking a "national remedial plan" to stabilize climate and restore Earth’s energy balance.
The District Court denied the Government's dispositive motions, describing the claims as unusually broad constitutional allegations tied to devastating planetary harm (Juliana v. United States, 217 F. Supp. 3d 1224).
The District Court declined to certify interlocutory review under 28 U.S.C. § 1292(b); the breadth of the claims presented substantial grounds for difference of opinion was noted by the Supreme Court.
The Government sought a stay of District Court proceedings from the Supreme Court pending its mandamus petition (No. 18-505) asking dismissal of the suit.
The Government argued the case exceeded Article III limits and raised unprecedented legal theories warranting mandamus and a stay.
The Ninth Circuit had twice denied the Government mandamus relief without prejudice, citing the early stage of litigation and potential narrowing of claims; trial had been scheduled but was stayed administratively.

Issue	Plaintiff's Argument	Defendant's Argument	Held
Whether a stay pending Supreme Court disposition of a mandamus petition is warranted	Juliana sought to proceed in district court to resolve constitutional claims and obtain remedial relief	Government argued Supreme Court should stay district proceedings because mandamus should be granted to dismiss as beyond Article III and based on novel theories	Stay denied without prejudice because adequate relief may be available in the Ninth Circuit; mandamus in Supreme Court not likely given alternative appellate remedies
Whether mandamus is appropriate to confine the district court to lawful jurisdiction	Plaintiffs argued district court has authority to hear constitutional claims and craft remedies	Government argued mandamus is appropriate because claims are unprecedented and outside Article III power	Mandamus not shown to have a "fair prospect" of success in the Supreme Court here because intermediate appellate review remains available
Whether the Government has shown irreparable harm from denial of a stay	Plaintiffs argued proceeding in district court is necessary and not irreparably harmful to Government	Government asserted proceeding would cause irreparable harm by forcing resolution of claims that allegedly exceed judicial power	Court found Government did not meet stay standard primarily because alternative relief in the Ninth Circuit remains available

Hollingsworth v. Perry, 558 U.S. 183 (stay/mandamus standards; mandamus prerequisites)
Cheney v. United States Dist. Court for D.C., 542 U.S. 367 (mandamus standards and appropriateness)
Roche v. Evaporated Milk Assn., 319 U.S. 21 (writ in aid of appellate jurisdiction)
Ex parte Peru, 318 U.S. 578 (mandamus ordinarily sought in intermediate appellate court)
Juliana v. United States, 217 F. Supp. 3d 1224 (D. Ore. 2016) (district court decision describing plaintiffs' climate-based constitutional claims)