Iowa is among a group of states that’s gone to court to challenge an E.P.A. ruling that forbids states from setting emission standards for new vehicles that’re tougher than the federal rules. This all started in December when the U.S. Environmental Protection Agency rejected California’s request for a waiver that would let California enforce stricter standards on carbon dioxide emissions from new vehicles. California officials have argued such emissions contribute to global warming.

Iowa’s attorney general says the case is important because if California is barred from enacting their rules, then every other state that tries to enforce statewide "Clean Air" rules to try to knock down carbon emissions would be prevented from doing so. The new Iowa Office of Energy Independence has recommended that Iowa join states "that have adopted or are considering adopting the California emission standards for passenger vehicles."

On Friday, the states of Iowa and Florida joined in California’s lawsuit that seeks court review of the E.P.A.’s decision. A total of 19 states, including Iowa, are now involved in this legal fight.