Montana v. Wyoming and North Dakota

Holding: Original; Montana has failed to state a claim for breach of the Yellowstone River Compact. Wyoming's more efficient irrigation systems are permissible under the Compact as long as the water conserved by those systems is used to irrigate the same acreage watered in 1950. (Kagan, J., recused).

Plain English Holding: Wyoming did not violate the Yellowstone River Compact by allowing Wyoming residents to implement more efficient irrigation systems on the farmland that existed when the compact was signed, even though the result is less water flowing downstream to Montana.

Judgment: Montana’s exception to the report of the Special Master is overruled., 7-1, in an opinion by Justice Thomas on May 2, 2011. Justice Scalia filed a dissenting opinion. (Kagan, J., recused).

Briefs and Documents

Merits Briefs

• Brief for First Interim Report of the Special Master
• Montana’s Exception and Brief
• Brief for Northern Cheyenne Tribe in Support of Montana’s Exceptions
• Wyoming’s Reply to Montana’s Exception
• Montana’s Sur-Reply

Amicus Briefs

• Brief for the United States as Amicus Curiae Opposing Plaintiff’s Exception

Certiorari-stage documents

• Wyoming's Brief in Opposition to Motion for Leave to File Bill of Complaint (unavailable)
• Amicus brief for Anadarko Petroleum Corporation (unavailable)
• Amicus Brief for the United States (unavailable)
• Amicus brief for the Northern Cheyenne Tribe (unavailable)
• Motion for Leave to File Bill of Complaint, Bill of Complaint, and Brief in Support (unavailable)
• Reply of Montana (unavailable)
• Motion to Dismiss Bill of Complaint (unavailable)
• Response to Wyoming's Motion to Dismiss Bill of Complaint (unavailable)
• Reply of respondent Wyoming in support of its Motion to Dismiss Bill of Complaint (unavailable)