California will unveil the first program to restrict CO2 emissions from automobiles on Monday. California has a long history of being an environmental leader. They often enact tough legislation that other states and countries follow. With the Bush administration's slack-ass attitude towards environmental legislation, the states have been taking the lead.
This policy has been really controversial, with the car companies (of course) crying that it will be very expensive. Some activists think its the wrong approach. They say we should be working to improve fuel efficiency, and that attacking CO2 emissions is not the most efficient way to do that.