Maine has joined a lawsuit to protect the ability of California and other states to set tougher car emissions standards than those required by the federal government.

On Thursday, the Environmental Protection Agency and the Transportation Department formally revoked the waiver allowing California to set stricter limits on tailpipe emissions than the federal government, as part of a broader effort to scale back federal rules requiring U.S. auto fleets to average nearly 51 miles per gallon by model year 2025, The Washington Post reported. Trump officials have drafted a plan to freeze federal mileage standards at roughly 37 miles per gallon though model year 2026.

Xavier Becerra, California’s attorney general, argues in the lawsuit filed in the U.S. District Court for the District of Columbia that the administration overstepped authority given by Congress in withdrawing a waiver California has used to cut greenhouse gas emissions linked to climate change, the Post reported.

In response, a coalition of 23 states and two cities has filed the lawsuit to protect that authority, and Maine Attorney General Aaron Frey announced Friday that he had joined the case. The stricter car pollution rules there have been adopted by 13 other states, including Maine.

“As one of the states to have adopted Advanced Clean Car Standards, Maine took an important step to confront the serious threat that climate change presents to its economy, environment, and citizens’ health,” Frey said in a news release. “It is long established that (a state) may protect its citizens by taking innovative steps to reduce emissions and promote the use of cleaner vehicles. Now, the federal government is trampling on this authority. This new federal regulation would only serve to increase emission pollution and decrease environmentally-friendly innovation.”

In 2012, California adopted the Advanced Clean Cars Program for cars and light duty trucks in model years 2017 through 2025. The news release said those changes would reduce carbon dioxide in the state by about 14.4 million metric tons a year by 2025 and 25.2 million metric tons a year by 2030. When accounting for emissions savings from other states that have adopted California’s standards, these emission reductions nearly triple.

The lawsuit accuses the National Highway Traffic Safety Administration of overstepping its authority and failing to assess the possible damage to the environment and public health.

In addition to Frey, attorneys general of Colorado, Connecticut, Delaware, Hawaii, Illinois, Massachusetts, Maryland, Michigan, Minnesota, Nevada, New Jersey, New Mexico, New York, North Carolina, Oregon, Pennsylvania, Rhode Island, Vermont, Virginia, Washington, Wisconsin and the District of Columbia; as well as the cities of Los Angeles and New York, have joined the lawsuit.