A major fight is shaping up in federal court over the Trump administration’s recently issued rules that rewrite how the government implements the Endangered Species Act.

The battle was broadened on Sept. 25 when attorneys general from 17 states, the District of Columbia and New York City filed a challenge to the regulations in U.S. District Court in San Francisco.

In their lawsuit, the plaintiffs, led by California Attorney General Xavier Becerra, contend that the set of three new final rules—published in the Federal Register on Aug. 27 by the U.S. Fish and Wildlife Service and  National Marine Fisheries Service— “fundamentally undermine and contradict” Endangered Species Act requirements.

Two of the regulations took effect on Sept. 26. The effective date for the third, which aims to expedite “interagency cooperation”  procedures in listing species as endangered, was extended to Oct. 28.  [View 8/12/19 ENR story on regulations here.]

Among other changes, the rules set a stricter definition of "critical habitat" needed for an endangered species to survive; end a practice of giving threatened species the same protections as endangered species; allow economic factors to be aired—though not as a decisive factor—when agencies determine whether to list a species as endangered.

In their filing, the AGs say that want the court to invalidate the regulations and reinstate the previous rules.

The Trump administration plans to defend its new rules vigorously against the challenges. Nick Goodwin, an Interior Dept. spokesperson, said in an emailed statement, “These are long overdue and necessary regulatory changes that will recover more imperiled species facing extinction than  previously accomplished over the span of this law.”

Goodwin added, “We will see them in court and we will be steadfast in our implementation of this important act to improve conservation efforts across the country.”

The administration also is expected to file a formal response to the AGs’ lawsuit in the district court.

The AGs' lawsuit follows a similar challenge that a group of environmental organizations filed on Aug. 21 in the same court . [View 8/21/19 ENR story here.]

District Court Judge Jon S. Tigar on Oct. 7 issued a ruling to "relate" the two cases. He is expected to formally consolidate the two later.

Kristen Boyles, a senior attorney with Earthjustice, said in a statement to ENR, “At this point, the environmental groups are not seeking to block the rules from taking effect.”

Boyles added, “We will be monitoring the use of the rules and will seek quick court relief if necessary to prevent species or habitat harm.”

In extending the interagency cooperation rule, the Fish and Wildlife and Marine Fisheries services said they had "received many questions" about implementation of the regulation rule needed more time to educate and train staff at their own and other federal agencies.