Court May Force Bush's Hand on Environment

The supreme court in Washington will bring its ultimate authority to bear for the first time today on the issue of global warming - hearing legal arguments in a case that environmentalists believe could have far-reaching consequences.

Twelve US states, led by California and Massachusetts and backed by several cities and environmental groups, have brought the case to try to force the Bush administration to regulate carbon dioxide emissions from cars and factories.

They are challenging an appeal court ruling that the Environmental Protection Agency (EPA) - an arm of the administration - was not obliged to regulate CO2

Carbon dioxide is recognised as the prime cause of the greenhouse effect that leads to global warming. Campaigners say that when the supreme court passes judgment in a few months' time, it will determine the pace and tone of America's approach to climate change.

If the states lose the action, tough new measures brought in by California to force car manufacturers to produce cleaner vehicles would instantly be imperilled, as the state's legal right to set its own emissions targets would be undermined.

Other states, mostly in the north-east, have followed California's example and introduced their own tougher restrictions on emissions. These would also be in doubt.

If the states win the action, say campaigners, the EPA would be forced to take a more active approach to controlling emissions. "It would send a powerful signal - not least to the markets - that the US is getting serious, and make real change more inevitable," said Josh Dorner, a spokesman for the Sierra Club, a leading US environmental organisation.

Under the Clinton presidency, the EPA took the line that it did have the authority to regulate CO2. But the Bush administration reversed that policy and, in 2003, the EPA announced that the gas was not a pollutant under the clean air act, and consequently it had no right to regulate it.

Since then, the White House has taken a consistent approach that voluntary measures are preferable to federally imposed solutions. It argues that the scientific causes of global warming remain insufficiently understood for tighter regulations to be merited.

The environmental group, Friends of the Earth (FoE), one of the participants in today's action, said the law appeared clear-cut. Under the clean air act, the EPA was obliged to regulate any pollutant "which may reasonably be anticipated to endanger public health or welfare" - including anything impacting on climate and weather. "This should be a fairly easy decision for the supreme court to make," said Sara Zdeb, FoE's legislative director.

However, the court is an unknown quantity on global warming. It has never dealt with the subject before, while two of its nine justices - the chief justice John Roberts and Samuel Alito - are relatively new to the court.

Besides California and Massachusetts, the states involved in the action are Connecticut, Illinois, Maine, New Jersey, New Mexico, New York, Oregon, Rhode Island, Vermont and Washington. The cities backing it include New York, Baltimore and Washington DC.