On November 29, 2016, eighteen states filed suit against the U.S. Fish and Wildlife Service and the National Marine Fisheries Service (collectively, the "Services") in federal court in the Southern District of Alabama challenging two controversial rules related to the designation of critical habitat for endangered or threatened species. One of the rules revised the definition of "adverse modification" of critical habitat, and the other rule clarified the criteria used by the Services when designating critical habitat. The two rules had been sharply criticized as a significant expansion of federal power because, as the critics argue, the rule gives the Services authority to designate almost any area as critical habitat and almost any action as an "adverse modification" of that habitat.

The states' primary argument is that the two critical habitat rules unlawfully expand federal regulatory authority over lands and waters beyond the scope of the federal Endangered Species Act. To highlight the expansion of regulatory authority, the states provided in their complaint the following extreme examples:

[U]nder the Final Rules, the Services could declare desert land as critical habitat for a fish and then prevent the construction of a highway through those desert lands, under the theory that it would prevent the future formation of a stream that might one day support the species. Or the Services could prevent a landowner from planting loblolly pine trees in a barren field if planting longleaf pine trees might one day be more beneficial to an endangered or threatened species.

The Services have not yet answered the complaint filed by the states. The Services, however, have filed a motion to dismiss on the grounds that the states do not have standing to challenge the two critical habitat rules. Environmental groups and industry groups are expected to intervene in the litigation.

As with many federal issues pending during the current changeover in the White House, it remains unclear how or whether the new Trump Administration will seek to influence the defense of the Services' critical habitat rules.