The US Supreme Court declined to hear an appeal from three conservation groups challenging President Trump’s plan to build a wall along the U.S.-Mexico border over potential environmental concerns.

The Center for Biological Diversity, the Animal Legal Defense Fund, and Defenders of Wildlife alleged in their lawsuits that Section 102(c) of the 1996 Illegal Immigration Reform and Immigrant Responsibility Act gave the federal government the ability to waive environmental laws in order to expedite the construction of barriers and roads like the border wall.

“(c) WAIVER.—The provisions of the Endangered Species Act of 1973 and the National Environmental Policy Act of 1969 are waived to the extent the Attorney General determines necessary to ensure expeditious construction of the barriers and roads under this section.”

The conservation groups argued that the waiver was unconstitutional and gave the Department of Homeland Security too much power in its ability to bypass the Endangered Species Act and National Environmental Policy Act. The border wall construction could potentially harm plants, wildlife habitats, and many coastal species.

The case was decided in February by US District Judge Gonzalo Curiel who granted summary judgment in favor of the Trump administration. Curiel did not find the 1996 law’s waiver provision unconstitutional. He held that the Department of Homeland Security should get wide discretion on border security issues and that the Trump administration did not abuse this discretion in proceeding with constructing border wall prototypes.