The court’s three liberals, Justices Ketanji Brown Jackson, Elena Kagan and Sonia Sotomayor, joined Chief Justice John Roberts and Justice Brett Kavanaugh in the 5-4 majority.
The court denied a motion Friday made by the two states, along with neighboring Colorado, to enter a consent decree on the subject and instead sustained an exception made by the United States.
The consent decree had outlined how New Mexico and Texas would resolve past discrepancies as to how the former delivers water to the latter. But the U.S. maintained that their proposed agreement was both incompatible with a historic compact and would require the federal government to adhere to protocols that it hadn’t approved.
“We agreed with the United States,” Jackson wrote in the opinion issued Friday morning.
“Although interstate compacts are (as the name suggests) agreements between States, ‘we have sometimes permitted the federal government to participate in compact suits to defend “distinctively federal interests,” Jackson wrote, citing a 1981 Maryland v. Louisiana case as precedent.
The current case has roots in the 1938 Rio Grande Compact — an agreement that served to oversee river use in three U.S. states through a debit-credit system that accounts for shifting hydrological conditions. Historically, New Mexico has obtained 57 percent of the domestic Rio Grande flow, while 43 percent has been sent to Texas.
Read more in a full report from our colleague Sharon Udasin at TheHill.com.