The litigation group Earthjustice, the sue-and-settle arm of Sierra Club, has joined other controversial environmental trial lawyer groups, such as Center for Biological Diversity, Environmental Defense Fund, Natural Resources Defense Council, and Union of Concerned Scientists, in a lawsuit to try and force EPA to keep Obama-era standards that environmental lawyers helped write. The now discarded additional regulations would have further limited carbon dioxide emissions from cars and light trucks for the model years 2022-25.

The estimates from 2012 were that the new regulations would reduce carbon dioxide emissions by over half a billion tons but there were concerns the EPA used "secret science" in the form of environmental claims that were outside public scrutiny and the Trump administration said the standards should be revised using transparent data.

Earthjustice lawyer Seth Johnson, who is co-counsel for the Sierra Club, said, “Once again ignoring the severe climate crisis facing our nation, this administration is turning its back on reality and science, in favor of its polluter buddies.”

But in natural gas, studies have shown the private sector has surpassed the emissions cuts that the also-dismissed Clean Power Plan mandated, eight years ahead of what the CPP wanted. And EPA now argues that the free market will do the same here, unless regulations give them a free pass to only achieve the Obama minimum standard.

Today's suit was filed in the United States Court of Appeals for the District of Columbia Circuit by other controversial environmental trial lawyer groups, such as Center for Biological Diversity, Environmental Defense Fund, Natural Resources Defense Council, and Union of Concerned Scientists, joining previous suits filed by California and over a dozen other Democratic states, along with business interests who will benefit if conventional automobiles are penalized by government.