San Francisco -

A federal appeals court hearing a case seeking to stop California's first-in-the-nation mandate requiring fuel producers to reduce greenhouse gas emissions is focusing on whether the law discriminates against out-of-state businesses.
A three-justice panel of the 9th U.S. Circuit Court of Appeals on Tuesday heard oral arguments about the constitutionality of California's "Low Carbon Fuel Standard," a piece of the state's landmark global warming law, AB 32.
The justices' questions focused on the law's reliance on a "carbon intensity score," which measures pollution from a fuel's entire life cycle, not just when it is burned in a vehicle.
Out-of-state refiners and ethanol companies say this discriminates against their products because transportation to California raises the score.
The state says the law does not discriminate and will spur clean-fuels innovation.