The Supreme Court questioned whether the Biden administration’s preferred test for determining jurisdiction for wetlands under the Clean Water Act is too broad during oral arguments on Monday.

The justices heard the case of Sackett v. EPA, in which Idaho landowners are challenging the agency’s determination that a property on which they wished to build a home was subject to regulation as one of the “waters of the United States” which fall under federal jurisdiction under the act.

The 2006 verdict in the case of Rapanos v. United States resulted in a splinter 4-1-4 ruling that provided two different tests for determining which wetlands and other waterways are protected under the CWA. The Sacketts, represented by the conservative nonprofit Pacific Legal Foundation, are asking the court to hold to a narrower definition favored by industry and farming groups.

[Related: Supreme Court to hear case on EPA’s Clean Water Act authority ]

The court began by debating the use of the term “adjacent” in the CWA. Pacific Legal Foundation attorney Damien Schiff said “mere adjacency itself cannot justify the agency’s statutory jurisdiction,” arguing for a limited view of the law that could exclude many neighboring wetlands without a direct surface connection.

The justices appeared skeptical of Schiff’s argument, with Chief Justice John G. Roberts Jr. asserting that a “train station is adjacent to the tracks, even though it’s not touching the tracks.”

Justice Kentanji Brown Jackson questioned why Congress would draw the line at abutting wetlands and neighboring wetlands when the original goal was to protect water quality, noting that both types of wetlands can ultimately impact water quality. Schiff said that when Congress passed the CWA and amendments it was trying to balance environmental concerns while preserving states’ authority over land and water resources.

Questioning administration

The court also appeared skeptical of the Biden administration’s preferred test for determining which wetlands are subject to regulation.

The EPA and Army Corps of Engineers are expected by the end of the year to finalize a new waters of the United States, or WOTUS, definition that relies upon the “significant nexus” test put forward by Justice Anthony Kennedy in his concurrence in the Rapanos case. Under this test wetlands that have a significant connection to a navigable water protected under the CWA could be subject to regulation, regardless of whether it is a surface connection.

Principal Deputy Solicitor General Brian Fletcher said that with this rule-making “the agencies are now doing what members of this court have repeatedly urged them to do by promulgating regulations that recognize and appropriately limit the coverage of the act.”

However, Justices Amy Coney Barrett and Clarence Thomas, both pointing to their childhoods in low-lying communities, questioned whether under a significant nexus test nearly any property could be regulated due to the presence of aquifers that ultimately drain into a protected waterway.

Fletcher said wetlands have a particular scientific definition that is reflected in the government’s regulation and enforcement. In response to concerns Schiff raised about the ambiguity of the law and how it affects potentially regulated landowners, Fletcher added that they would be able to seek clarification from the agency at no cost. 

Justice Sonia Sotomayor said she recognized that there was sentiment that the significant nexus test may be too imprecise to survive, and both she and Justice Elena Kagan questioned whether there was a third test the court could adopt other than the two proposed by Schiff and Fletcher that could clarify which wetlands are subject to regulation.

Schiff said he believed the middle position would examine the nature of a barrier and consider whether it is natural, such as a berm, or a permanent barrier, such as the road that separates the Sacketts’ property from nearby Priest Lake. However, Schiff said this would not be a satisfactory middle position “because it still doesn’t really afford appropriate fidelity to the text.”

Fletcher again pointed to the agencies’ rule-making process and noted that they took comment on how to “crystallize” the significant nexus test and provide further clarification in order to address concerns raised by the Obama administration’s 2015 WOTUS definition.