U.S. Senate vote to nix California tailpipe emissions standard blocks 17 other states

[Igel]

8. I'd guess supremacy clause

The EPA issued a waiver that allowed California to impose stricter regulations than the Congress-authorized EPA issued.

To roll them back just requires revoking the waiver. Oddly, that's an executive action as permitted by Congress, yet the courts seem to be saying that the executive has no control over the waiver and others say that Congress doesn't.

Personally, that tells me that some subset of the executive branch functions as its own branch of government, and once set in motion is untrammeled by pesky notions of accountability, checks and balances, and democracy. Democracy gets a say--one time and that's it. Rather like there are "democracies" where a president/caudillo gets elected once and says, "I am elected as president" ... And 20 years later is still "elected as president." (Abbas comes to mind. So does Hamas, even if those elected are now dead and their replacements are in charge ... sort of.)