California's clean vehicle rules can now be enforced by US environmental regulators

US environmental regulators are proposing to approve California's rules for controlling emissions from new vehicles and engines. This means these state-level regulations will become federal law, making them enforceable nationwide by the US environmental regulators.

California has long set its own, stricter, vehicle emission standards. Other states often adopt these rules. This approval means that the US environmental regulators will now enforce California's standards, not just the federal ones. This makes it harder for vehicle manufacturers to challenge these rules in court, as they are now backed by federal authority.