The court documents filed in a Washington appeals court argue that Republican President Donald Trump's move -- which eliminated greenhouse gas standards on automobiles and placed a host of additional rules in jeopardy -- was illegal.

The 2009 "endangerment finding" said that greenhouse gases harm public health, and was core to decades of federal climate policy.

Its rollback was broadly condemned by environmental groups and many Democrats, and legal action was expected.

The case was brought by a broad coalition of groups including the American Lung Association, the Clean Air Council, the Union of Concerned Scientists, the Sierra Club and the Center for Biological Diversity.

"We're suing to stop Trump from torching our kids' future in favor of a monster handout to oil companies," said David Pettit, an attorney at the Center for Biological Diversity, in a statement.

"Nobody but Big Oil profits from Trump trashing climate science and making cars and trucks guzzle and pollute more. Consumers will pay more to fill up, and our skies and oceans will fill up with more pollution. The EPA's rollbacks are based on political poppycock, not science or law, and the courts should see it that way."

Trump, 79, has dismissed concerns that the repeal could cost lives by worsening climate change, reiterating his belief that human-caused global warming is a hoax.

The administration has framed the measure as a cost-saving move, claiming it would generate more than $1 trillion in regulatory savings and bring down new car costs by thousands of dollars.

The 2009 "endangerment finding" was a determination based on overwhelming scientific consensus that six greenhouse gases threaten public health and welfare by fueling climate change.

It came about as a result of a prolonged legal battle ending in a 2007 Supreme Court decision, Massachusetts v. EPA, which ruled that greenhouse gases qualify as pollutants under the Clean Air Act and directed the EPA to determine whether they pose a danger to public health and welfare.

While it initially applied only to vehicle emissions, it later became the legal foundation for a broader suite of climate regulations, which are now vulnerable.