Environmentalists scored a rare and somewhat muddled victory in the U.S. Supreme Court on Thursday. For the court's newest justice, Brett Kavanaugh, victory belonged to the late Justice Antonin Scalia.

In County of Maui v. Hawaii Wildlife Fund, the justices were asked if the Clean Water Act requires a permit when pollutants originate from a point source, such as a sewage treatment plant, but are conveyed to navigable waters by a nonpoint source, such as groundwater.

Parties on both sides claimed their positions were supported by Scalia's 2006 plurality opinion in the case Rapanos v. United States, an opinion described as a "quagmire" interpretation of "waters of the United States." The relevant part of the fractured 4-1-4 Rapanos opinion for the Maui case was that the CWA "does not forbid the 'addition of any pollutant directly to navigable waters from any point source,' but rather the 'addition of any pollutant to navigable waters.'"

The 6-3 Maui majority, which included Kavanaugh, ruled that the CWA requires a permit when there is a direct discharge from a point source into navigable waters or there is the "functional equivalent of a direct discharge" from the point source.

The majority, led by Justice Stephen Breyer, rejected as too broad a test used by the U.S. Court of Appeals for the Ninth Circuit and as "neither persuasive nor reasonable" a narrow test urged by Maui and the U.S. solicitor general. The majority's test was seen as a compromise, but the ruling was hailed as upholding "the intent of the Clean Water Act to protect and restore the quality of the nation's waterways," said environmental scholar Michelle Nowlin of Duke University School of Law.

Although the majority cited Scalia's 2006 plurality opinion in Rapanos only once for support, Kavanaugh devoted a three-page concurring opinion to explaining how the majority opinion "adheres to the interpretation" of the CWA by Scalia.

In Rapanos, Kavanaugh wrote, Scalia said the CWA does not "merely forbid the 'addition of any pollutant directly to navigable waters from any point source,' but rather the 'addition of any pollutant to navigable waters.' Thus, from the time of the CWA's enactment, lower courts have held that the discharge into intermittent channels of any pollutant that naturally washes downstream likely violates §1311(a), even if the pollutants discharged from a point source do not emit 'directly into' covered waters, but pass 'through conveyances' in between."

Kavanaugh continued: "The statute does not establish a bright-line test regarding when a pollutant may be considered to have come 'from' a point source. The source of the vagueness is Congress' statutory text, not the court's opinion. The court's opinion seeks to translate the vague statutory text into more concrete guidance."

Justice Clarence Thomas, joined by Justice Neil Gorsuch, dissented. The Rapanos ruling did not resolve the Maui case, Thomas asserted.

"That plurality opinion, which I joined, observed that lower courts have required a permit when pollutants pass through a chain of point sources," he wrote. "But we expressly said in Rapanos that 'we did not decide this issue.' We are not bound by dictum in a plurality opinion or by the lower court opinions it cited."

Justice Samuel Alito Jr. also wrote a dissenting opinion. He argued that he would interpret the statute to require a permit "when a pollutant is discharged directly from a point source to navigable waters." He claimed, in a footnote, that Scalia's opinion in Rapanos supported his conclusion.

Kavanaugh and Alito are not alone in finding support in Scalia's opinion for their views of the CWA. In 2017, President Donald Trump issued an executive order directing the U.S. Environmental Protection Agency to revise its 2015 Waters of the United States rule "in a manner consistent with the opinion of Justice Antonin Scalia" in Rapanos.

Hunton Andrews Kurth partner Elbert Lin argued for Maui County at the Supreme Court. Contract records show Maui County first contracted with the predecessor firm Hunton & Williams in 2013 for $250,000. Subsequent amendments, including $500,000 for litigation in the U.S. Supreme Court, pushed the total contract to $4.3 million.