WASHINGTON – A prominent member of the Supreme Court bar, the small circle of lawyers who regularly appear before the justices, infuriated environmental groups by presenting an argument the groups say is demonstrably incorrect.

The claim a month ago by Washington attorney Carter Phillips that the federal government had changed course in regulating emissions from coal-fired power plants is simply not true and a paper trail of the industry’s own documents proves it, the groups say.

The case, Environmental Defense v. Duke Energy Corp., could determine the fate of an Environmental Protection Agency initiative targeting some of the biggest utilities in the nation. Phillips, representing Duke, is managing partner at the Washington office of the law firm Sidley Austin and has argued more than 50 cases at the Supreme Court.

“These companies are bent on getting away with 20 years of illegal pollution by trying to deceive the Supreme Court,” said Natural Resources Defense Council clean air director John Walke, who is a former EPA attorney.

Utility industry attorney Scott Segal jumped to Phillips’ defense, saying that “for these environmental groups to go after one of the best lawyers in the country is a travesty. Phillips leads a legal dream team with a spotless record.” Segal, a partner at the law firm Bracewell & Giuliani, was responding to a list of questions a reporter sent to Phillips’ office at Sidley Austin. With the case pending before the Supreme Court, Phillips did not respond.

The government enforcement action against Duke is one of more than a dozen brought by the Clinton administration in 1999 and 2000.

It is aimed at forcing power companies to install the latest pollution-control equipment on aging coal-fired plants which were renovated so they could be operated longer hours.

On Nov. 1, Phillips told the justices: “Our basic argument is that all along” EPA interpreted the regulatory requirements “in a certain way. And then 19 years later, they reversed course” and suddenly sued the companies.

The environmental groups say internal industry documents clearly show that Duke understood long ago that EPA was interpreting the requirements in the same way it did in 1999 when the government went to court. Some of the documents are part of the record before the Supreme Court and all were brought to light in lawsuits against Duke and other utilities.

Among the documents, according to a Justice Department court filing, are 10 memos from an industry trade association spelling out the EPA’s position for Duke starting in the late 1980s. It was the same regulatory approach EPA took a decade later when it sued the company. The Justice Department document was filed publicly in 2003, but at Duke’s request it was put under seal, barred from public view.

The day after the Supreme Court argument, the Natural Resources Defense Council provided journalists with copies of industry documents the environmental groups say contradict the tack taken by Duke’s lawyer before the high court.

One of them is a Duke company training guide on environmental compliance from 1991 that appears to characterize the EPA’s approach in the same way the federal agency did nine years later when it sued Duke.

George Washington University law professor Jonathan Turley reviewed some of the industry files and said, “I find the statements Phillips made hard to square with these documents.”

Turley said the complexity of the case makes it easy to suggest uncertainty or confusion, and that “Phillips’ comments in court are more likely to be treated as attorneys gilding the lily for their client” rather than attempting to mislead.

The dispute between the utilities and the environmental groups and Justice Department lawyers is whether emissions increases should be measured on an annual basis or under a two-part test.

The industry says EPA regulations always have required an hourly rate increase in emissions before measuring for annual increases.