The EPA is planning to cancel the special waiver that California has relied on since 1970 to set its own emissions standards, according to a Bloomberg report.

As part of its plan to reverse a program to steadily tighten fuel economy standards that it coordinates with California and the National Highway Traffic Safety Administration, the EPA has drafted a proposal to freeze those standards in 2021 and prevent California from setting its own standards, the Bloomberg report says.

California has had the right to set its own standards since President Richard Nixon signed the Clean Air Act Extension in 1970, because California had already implemented its own emissions limits to clean up the smog that got trapped in the Los Angeles basin. The Act required the EPA to grant California special waivers to set its own tighter standards, as long as they meet certain requirements, because it already had a program in place to mitigate pollution in LA. The steady sunshine there creates more smog, and cool ocean air blowing over the coastal mountains traps the smog in populated inland valleys.

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Now, for the first time, the EPA is planning to cancel that waiver, according to the draft proposal. The Bloomberg report cited sources familiar with discussions, but not authorized to talk about the proposal publicly.

The EPA is involved in fuel economy standards because of a 2007 Supreme Court ruling that required the EPA to regulate carbon-dioxide emissions, which can only be done by improving fuel economy. Since 2009, the EPA has worked with NHTSA and the California Air Resources Board to coordinate fuel economy standards. The NHTSA, part of the Department of Transportation, officially sets fuel economy standards, while the EPA regulates emissions including carbon dioxide.

California and 16 other states (plus Washington, D.C.) announced last month that they would sue the EPA over its plan to reverse scheduled increases in fuel economy standards for the 2020 through 2025 model years. The 16 states (plus D.C.) that sued include 12 that follow California's tighter standards. Other states are forbidden from setting their own emissions standards under the Clean Air Act, but they can choose to follow California's standards instead of the EPA's.

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Congress required fuel economy standards to be raised for the first time since 1992, to at least 35 mpg, under the Energy Independence and Security Act, signed by President George W. Bush in 2007. After the 2008 election, the Obama Administration was left to implement the increases in the face of the 2007 Supreme Court ruling on CO2 emissions. It set a rising curve of standards through 2025, with a "mid-cycle review" scheduled for 2017—after a new President would take office—to address whether standards following that were realistically achievable.

During the 2016 election, in the final years of the Obama Administration, the EPA documented its case for maintaining the standards in a 1,200-page review. After Donald Trump was elected in November 2016, the EPA finalized its decision to keep the increasing standards in place through 2025 in the final month of Obama's presidency.

As soon as Trump took office, the automakers met with the new Administration to ask that the mid-cycle review be reopened with an eye toward loosening the standards. After Scott Pruitt was appointed EPA Administrator he reopened the review, providing a 38-page legal justification.

EPA administrator Scott Pruitt [photo from 2014]

EPA administrator Scott Pruitt [photo from 2014]

This week, the Science Advisory Board, an EPA watchdog, took issue with Pruitt's justification, saying it didn't pass scientific muster, and the board plans to review the decision.

After the 17 states decided to sue and a public uproar ensued, the automakers went back to the Trump Administration and reiterated that the most important thing to them was to have a single set of fuel economy standards that they could count on.

Following that meeting, the EPA reportedly added the proposal to revoke, or circumvent and nullify the California waiver, effectively requiring that all states follow the same emissions and fuel economy standards.

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If the EPA attempts to revoke or nullify California's waiver and the states' lawsuit continues, however, fuel-economy standards are likely to be tied up in court with an uncertain outcome for years.

"It's very unclear what they're doing," says Simon Mui, a senior scientist at the Natural Resources Defense Council. "From a legal standpoint, this has never been done before."