The move would theoretically provide ammunition for lawsuits challenging the rollback, which would also nullify California's ability to set more stringent emissions rules. Another 12 states follow California's lead on tougher regulations.

Neither the EPA nor the NHTSA had responded to the lawsuit as of this writing, but it's expected that they'll fight the case. The rollback represents a significant part of the President's deregulatory push, and that push might fizzle out if there are significant flaws in the evidence. As it stands, lawsuits directly challenging the rollback could stave off its effect for a while, regardless of whether or not California obtains the justifications or wins its larger court battle.