Updated at 6:19 p.m. EST to include comments from industry attorney Scott Segal.

A federal court decided this afternoon that it would not stop U.S. EPA's new greenhouse gas regulations from taking effect on Jan. 2, 2011, despite pleas from dozens of industry groups, states and free-market advocates.

The ruling by the U.S. Circuit Court of Appeals for the District of Columbia will allow the Obama administration to continue with its plan to put the first nationwide limits on greenhouse gases from cars, light-duty trucks and large facilities such as coal-fired power plants, oil refineries and factories.

In their requests for a stay of the regulations, businesses had argued that the new greenhouse gas regulations would harm them by adding to the cost of doing business. States such as Texas argued that EPA's rules needed to be stopped because they were trampling on the sovereign rights of states.

It could be quite a while before the court decides whether the rules are legal under the Clean Air Act, but in the meantime, the challengers "have not satisfied the stringent standards" that justify stopping agency rules as court proceedings unfold, the ruling said.

Barring action by Congress, there is now nothing that could stop the agency from moving forward with its rules.

David Doniger, the policy director of the Natural Resources Defense Council's Climate Center, said the decision is encouraging, though it does not indicate whether the court will eventually agree to uphold the rules.

"These cases were brought to dress up the political argument that the big polluters are making to Congress, about how the sky will fall," said Doniger, who helped write the NRDC's briefs in support of EPA. "You can say anything you want to Congress, but when you bring a case and ask a court for a stay, you have to prove it to the court. They failed."

Scott Segal, an industry attorney at Bracewell & Giuliani LLP, cautioned against reading too much into the ruling, saying that a stay is always a long shot. Because of the uncertainty surrounding the regulations, the court's preliminary decision could end up slowing construction on new power plants and other major construction projects, he said.

"Given the state of the economy, the decision is certainly not a welcome holiday present," Segal said in a statement.

Click here to read the ruling.