Democratic lawmakers and several states urged a D.C. federal court Monday to hear out challenges by environmental groups and tribes to President Donald Trump’s decision to shrink national monuments in Utah, joining a host of others questioning Trump’s authority under the Antiquities Act.

Over two dozen Democratic senators and almost 100 Democratic representatives said in an amicus brief that while the Antiquities Act gave presidents the ability to act to protect landmarks from destruction, “Congress did not … give presidents the authority to diminish or abolish existing national monuments, which would have ill-served the preservationist goals of the Antiquities Act and Congress’ own constitutional prerogatives.”

The federal government asked the court in early October to throw out the consolidated suits opposing the reduction of the Grand Staircase-Escalante and Bears Ears national monuments. The government argued that the 1906 Antiquities Act gives the president the power to reduce monuments to the smallest size he deems appropriate to protect natural and cultural assets, and that nothing in the law says he can’t modify a previous president’s designations.

The federal government has argued that since 1906, Congress’ passive “acquiescence” when presidents have modified their predecessors’ monument designations gives a president the authority to downsize. But, the Democratic lawmakers contend, “pure inaction by a subsequent Congress is never grounds for concluding that presidential conduct has altered the meaning of a law.”

“The administration highlights instances from the 20th century in which presidents modified national monument boundaries, but it fails to show that Congress did anything to ratify the exercise of such power or that these previous modifications provided any compelling reason for Congress to challenge the president about the correct interpretation of the Antiquities Act,” the lawmakers said.

Constitutional Accountability Center President Elizabeth Wydra, who represents the congressional members, said in a statement Tuesday that with the law, Congress gave presidents the power to create but not to reduce the size of monuments.

“Just because President Trump is willing to do whatever his oil and gas mining supporters want doesn’t make such a power grab lawful,” Wydra added. “We hope the court agrees.”

In a separate brief, Washington, California, New York and eight other states also said Trump’s reductions exceeded his authority and that the Antiquities Act is “a one-way ratchet in favor of preservation.”

The states also contended that Trump’s actions could jeopardize other monuments in their jurisdictions and that his “unlawful interpretation of his authority under the Antiquities Act threatens the long-term vitality of these national monuments and subjects all presidentially created national monuments, regardless of the time of creation, to the whim of future administrations.”

In December, Trump issued two presidential proclamations modifying the Grand Staircase-Escalante and Bears Ears national monuments, which were designated by former presidents Bill Clinton and Barack Obama, respectively. One of Trump’s proclamations divided the Grand Staircase-Escalante monument into three new areas and reduced it from 1.7 million acres to about 1 million acres. The other divided Bears Ears into two areas and reduced it from 1.35 million acres to about 200,000 acres.

The monuments were originally requested by conservationists and Native American tribes and acclaimed after their designation for protecting important natural, cultural, historic and scientific sites and relics. Those groups sued over the Trump administration’s modifications, asserting they violated the Constitution’s separation of powers doctrine by taking power Congress reserved for itself, as well as the take care clause, which establishes that a president “take care that the laws be faithfully executed.”

On Nov. 15, the environmental groups and the tribes fought back against the federal government’s bid to dodge their lawsuits. In their brief defending their lawsuit challenging the Bears Ears reduction, the Hopi Tribe, Navajo Nation, Ute Indian Tribe, Ute Mountain Ute Tribe and Zuni Pueblo said the monument contains many important cultural sites, some of which date back 13,000 years, including petroglyphs and painted handprints that tribal members visit.

The tribes also contended that “the real reason for the rollback” was “to pave the way for extractive development.”

In another amicus brief Monday, the National Congress of American Indians and the Association on American Indian Affairs said that Trump’s reduction of Bears Ears “erodes the progress the federal government has made toward protecting tribal cultural heritage and supporting tribal self-government” and “violates the Antiquities Act by failing to account for the thousands of tribal objects and places of historic interest throughout the monument and the threats these historic objects will now face.”

In addition, “other federal laws are inadequate on their own to protect the landmarks, structures and other objects of historic interest that were part of the original monument,” the groups said.

Others weighing in in support of the plaintiffs in amicus briefs Monday were the National Parks Conservation Association, Outdoor Alliance, Conservatives for Responsible Stewardship, a group of local elected officials in Utah and an alliance of archaeological associations.

The members of Congress are represented as amici by Elizabeth B. Wydra, Brianne J. Gorod and Brian R. Frazelle of Constitutional Accountability Center.

The states of Washington, California, Hawaii, Maine, Maryland, New Mexico, New York, Oregon, Rhode Island, and Vermont and the Commonwealth Of Massachusetts are represented as amici by their respective attorneys general.

The National Congress of American Indians and the Association on American Indian Affairs are represented by the NCAI’s Derrick Beetso, the AAIA’s Shannon Keller O’Loughlin, and Sam Hirsch, Thomas J. Perrelli and Leonard R. Powell of Jenner & Block LLP.

The government is represented by Jeffrey H. Wood, Romney S. Philpott and Judith E. Coleman of the U.S. Department of Justice‘s Environment and Natural Resources Division.

The Hopi Tribe, Ute Mountain Ute Tribe and Zuni Tribe are represented by Natalie Landreth and Matthew Campbell of the Native American Rights Fund.

The Natural Resources Defense Council is represented by its own Sharon Buccino, Jacqueline M. Iwata, Katherine Desormeau, Ian Fein and Michael E. Wall.

Utah Diné Bikéyah, Friends of Cedar Mesa, Archaeology Southwest, Conservation Lands Foundation Inc., Patagonia Works, The Access Fund, the National Trust for Historic Preservation and the Society of Vertebrate Paleontology are represented by James T. Banks, Adam M. Kushner, Douglas P. Wheeler III and Hunter J. Kendrick of Hogan Lovells.

The Wilderness Society, Defenders of Wildlife, Grand Canyon Trust, Great Old Broads for Wilderness, Western Watersheds Project, WildEarth Guardians, Sierra Club and Center for Biological Diversity are represented by Heidi McIntosh, James Pew and Yuting Yvonne Chi of Earthjustice.

The Navajo Nation is represented by Attorney General Ethel Branch and Assistant Attorney General Paul Spruhan of the Navajo Nation Department of Justice.

The Ute Indian Tribe is represented by Jeff Rasmussen and Rollie Wilson of Fredericks Peebles & Morgan LLP.

Grand Staircase Escalante Partners, Society of Vertebrate Paleontology and Conservation Lands Foundation are represented by Gary S. Guzy, John Mizerak and Shruti Chaganti Barker of Covington & Burling LLP.

Southern Utah Wilderness Alliance is represented by its own Stephen H.M. Bloch, Landon C. Newell and Laura E. Peterson.

The first set of consolidated cases is The Wilderness Society et al. v. Donald J. Trump et al., number 1:17-cv-02587, and Grand Staircase Escalante Partners et al. v. Donald J. Trump et al, number 1:17-cv-02591, in the U.S. District Court for the District of Columbia.

The second set of consolidated cases is Hopi Tribe et al. v. Donald J. Trump et al, number 1:17-cv-02590, Utah Diné Bikéyah et al. v. Donald J. Trump et al., number 1:17-cv-02605, and Natural Resources Defense Council et al. v. Donald J. Trump et al., number 1:17-cv-02606, in the U.S. District Court for the District of Columbia.