The U.S. Supreme Court on April 17 heard oral arguments in two related cases examining whether the requirements of the Endangered Species Act supersede those of the Clean Water Act. The cases, which pit the National Association of Home Builders and the Environmental Protection Agency against environmental group Defenders of Wildlife, center on whether EPA must consider needs of endangered species before transferring authority to a state for the National Pollutant Discharge Elimination System permitting program. Defenders of Wildlife says EPA is required to do so under “plain terms” of the Endangered Species Act, a conclusion that was upheld by a federal appeals court.

But home builders and EPA argue that the Clean Water Act requires EPA to approve state permit programs if nine specific criteria are met, none of which involve the Endangered Species Act. NAHB says that Congress did not intend for the courts to add a tenth criterion: considering the needs of endangered species.

The high court is expected to issue a decision on the case early this summer.