Alec Sweet

Document Type

Supreme Court Commentaries

Publication Date



Equitable Apportionment, Water, Rivers, Sovereignty

Subject Category

Constitutional Law | Environmental Law | Law | Water Law


Contemporaneous with significant climate change and heightened environmental concerns, the Supreme Court has seen an increasing number of water-related lawsuits between states. These lawsuits include disputes over water storage and water compacts as well as disputes over water usage affecting aquaculture. Scientists predict that in the future, the United States could face rising temperatures, droughts, and natural disasters. If states cannot cooperate to conserve the water they share, these catastrophes could cause immense suffering and numerous conflicts between states. The Supreme Court needs a consistent doctrine to apply in water disputes.

In prior disputes over surface water, the Court has applied the doctrine of equitable apportionment, determining the percentage of the disputed water each party is allowed to use. In Mississippi v. Tennessee, the Court was presented with a case of first impression and had to decide whether to extend the doctrine of equitable apportionment to ground water. There, the Court ruled in favor of Respondent Tennessee—extending the equitable apportionment doctrine and endorsing a flexible approach that encourages states to negotiate their use of a shared water resource. In ruling for Tennessee, the Court rejected Petitioner Mississippi’s arguments regarding state sovereignty and Mississippi’s inherent rights to the contested water.