Five Native American tribes filed suit [complaint, PDF] Monday against US President Donald Trump after he announced his decision to reduce the size of both Utah’s Bears Ears National Monument by nearly 90 percent and the Grand Staircase Escalante National Monument [proclamations] by nearly 50 percent.

The Hopi, Navajo Nation, Ute Mountain Ute Tribe, Pueblo of Zuni and Ute Indian tribes argue that the attempt to revoke a national monument violates the Antiquities Act of 1906 [text, PDF], which provides that, “[t]he President, may … declare by public proclamation historic landmarks, historic and prehistoric structures, and other objects of historic or scientific interest that are situated on land owned or controlled by the Federal Government to be national monuments.” The tribes claim that the act does not give the president authority to revoke or abolish monuments, nor does it give the president authority to modify or diminish national monuments.

The tribes are asking for immediate relief to stop the orders from taking effect before the case is heard by the court. Ultimately, they are asking that the proclamation be deemed unconstitutional and not be implemented.