Environmentalists frustrated by the federal government's failure to raise auto mileage standards took their battle to California, and May 2 won an important victory: The California State Senate passed a bill capping the levels of greenhouse gases that can be spewed by cars and light trucks. If signed by Gov. Gray Davis, the bill would become the first law in the U.S. to directly cap such emissions of greenhouse gases, a regulatory strategy already in use in Europe and Japan, according to a Wall Street Journal story by Jeffrey Ball. Launched with little fanfare last year by a group of San Francisco-area activists, a version of the bill passed the state's Assembly in January. But it gained the active backing of national environmental groups in recent weeks as a back-door way to improve fuel efficiency, according to the Journal. That came after the auto industry in March quashed a proposal in Congress for a big increase in federal auto-mileage standards, which are designed to encourage fuel conservation by requiring automakers to ensure that their vehicles, on average, reach certain levels of efficiency. California, the largest auto market in the United States, has often led the way in passing clean-air standards, and the legislation could trigger, by the 2009 model year, a change in the kind of cars and trucks that consumers see in showrooms across the country, according to the Journal. This could occur because it is impractical for automakers to build different vehicles to meet different emissions requirements. The effort also marks the latest sign that states are starting to act on their own to tackle climate-change issues, running ahead of Congress and the Bush administration. Already, environmentalists in New York say they hope soon to start floating in Albany their own proposal to limit carbon dioxide emissions from cars. Any such moves by states are likely to help rekindle the same debate in Washington; Democrats are widely disappointed at their failure to include higher mileage standards in the energy bill moving through Congress.