A majority of the Supreme Court seemed skeptical of the Biden administration’s defense of the Environmental Protection Agency’s authority to protect wetlands from pollution under the Clean Water Act on Monday, in the first session of oral arguments in the court’s new term.

At the same time, however, some conservatives on the bench seemed to reject an argument from an opposing lawyer suing the federal government that would severely limit EPA’s ability to regulate.

The long-running dispute centers on an Idaho couple who were hoping to build a home on new property in 2007 but received a stop work order from the EPA. The agency asserted that the property contained “navigable waters,” or wetlands subject to Clean Water Act protections.