Washington ? The Supreme Court entered the debate over global warming Monday, agreeing at the urging of environmentalists to rule on whether new cars, trucks and power plants must be further regulated to slow climate change.

The court’s action gave a surprising, if tentative, victory to 12 “blue states” and a coalition of environmentalists who say the federal government must restrict the exhaust fumes that contribute to global warming. Their appeal accused the Environmental Protection Agency of having “squandered nearly a decade” by failing to act.

The court voted to take up the issue over the objection of the Bush administration. Its lawyers questioned whether the government can and should “embark on the extraordinarily complex and scientifically uncertain task of addressing the global issue of greenhouse gas emissions” by regulating motor vehicles sold in the United States.

The case, to be heard in the fall, could be one of the most important environmental disputes ever to come before the court. If they win, environmental advocates said, auto makers could be forced to produce a fleet of vehicles that emit less pollution.

“Everything now hinges on what the Supreme Court does,” said David Bookbinder, a lawyer for the Sierra Club, one of the environmental groups that pressed the issue.

In other decisions Monday, justices:

l By a 6-3 vote, said Vermont’s limits on contributions and spending in political campaigns are too restrictive and improperly hinder the ability of candidates to raise money and speak to voters.

l Decided by a 7-2 vote that prosecutors’ failure to submit to a jury a factor used in sentencing is not grounds for automatic reversals of convictions.

l By a 6-3 vote, said parents cannot collect fees for experts they use while prevailing in lawsuits seeking to force public school districts to pay for the private education of their disabled children.

l Ruled 5-4 that defendants are automatically entitled to a new trial if their choice of a privately retained defense lawyer is wrongly blocked.