The Bush administration has drafted regulations that would ease pollution controls on older, dirtier power plants and could allow those that modernize to emit more pollution, rather than less.

The language could undercut dozens of pending state and federal lawsuits aimed at forcing coal-fired plants to cut back emissions of harmful pollutants such as sulfur dioxide and nitrogen oxide, said lawyers who worked on the cases.

The draft rules, obtained by The Washington Post from the Natural Resources Defense Council, an advocacy group, contradict the position taken by federal lawyers who have prosecuted polluting facilities in the past, and parallel the industry's line of defense against those suits. The utilities, and the proposed new rules, take the position that decisions on whether a plant complies with the regulations after modernization should be based on how much pollution it could potentially emit per hour, rather than the current standard of how much it pollutes annually.

Under the new standard, a modernized plant's total emissions could rise if the upgrade allowed it to operate longer hours. In court filings, the EPA estimated in 2002 that an hourly standard would allow eight plants in five states -- including Maryland, Virginia and West Virginia -- to generate legally as much as 100,000 tons a year of pollutants that would be illegal under the existing New Source Review rule. That equals about a third of their total emissions.

EPA spokeswoman Eryn Witcher said the administration believes the existing power plant rule is no longer necessary because of other regulatory initiatives. She said a newer and different regulation designed to cut pollution from eastern power plants, the Clean Air Interstate Rule, would achieve greater pollution reductions than the New Source Review modernization guidelines.

"We are committed to permanent significant emissions reductions from power plants because what matters is environmental results, and we get far better results under the Bush administration's Clean Air Interstate Rule, which cuts emissions by 70 percent," she said. That rule sets a long-term cap that would cut industry-wide emissions over the next decade and allow less-polluting plants to sell credits to dirtier facilities to reach the overall goal.

But John Walke, NRDC's clean-air director, said: "This radical proposal is a 180-degree flip-flop from what the administration has been arguing in court. Instead of protecting public health, now EPA wants to protect the polluters. The proposal would completely sabotage clean-air law enforcement, and it would be open season for power plants to pollute even more than they do now."

The administration's new version of New Source Review marks the latest salvo in a regulatory and legal tug of war over how best to regulate aging plants that are major contributors to air pollution, producing much of the sulfur dioxide and nitrogen oxide emissions, especially in the East. Those two pollutants cause more than 20,000 premature deaths a year, studies show.

Power plants account for two-thirds of the country's sulfur dioxide emissions and 22 percent of its nitrogen oxide pollution. Both have been shown to cause respiratory and heart disease.

Under the Clean Air Act, utilities must install new pollution controls when they engage in "major modifications," a requirement whose interpretation has sparked heated debate. Clinton administration officials began prosecuting utility companies in the mid-1990s for failing to comply, but Bush argued that this approach was too punitive. The administration sought to revise the rule so that new pollution controls would be required only when the cost of a plant upgrade amounted to 20 percent of its total value.

A federal court blocked Bush's proposal from taking effect nearly two years ago, prompting the EPA to come up with another approach. Now, the agency wants to use the amount of pollution a plant emits, rather than cost of an upgrade, to determine whether scrubbers are required.

The EPA proposal calls for the government to judge aging power plants by comparing "the maximum hourly emissions achievable at that unit during the last five years to the maximum hourly emissions achievable at that unit after the change" to determine if the company is required to install anti-pollution scrubbers.

New York state Attorney General Eliot L. Spitzer, who has taken legal action against six New York plants and 22 out-of-state plants for violating the Clean Air Act, said in an interview that the new rule "would be devastating to all New Source Review prosecutions, and reflects a fundamental, and what we consider an improper, new interpretation of the statute. . . . It would make our enforcement efforts much more difficult, if not impossible."

Eric Schaeffer, who headed the EPA's Office of Regulatory Enforcement before resigning in protest in February 2002, said the new rule undermines the original aim of the law, which was to slowly bring older plants into compliance with stricter air laws.

"Under this proposal, it would never happen," Schaeffer said.

In documents justifying its proposal, the EPA cites a June decision by the U.S. Court of Appeals for the 4th Circuit in Richmond, which sided with utilities in finding that it made more sense to judge them by hourly pollution levels. The agency is appealing that decision, with its lawyers calling the ruling "wrongly decided" and "fundamentally flawed in its analysis" of the Clean Air Act. Yesterday the 4th Circuit rejected that appeal, so the EPA must decide whether to take the case before the Supreme Court.

In another case, however, the U.S. Court of Appeals for the District of Columbia Circuit rejected the hourly test in a June ruling, saying the government should evaluate polluters by their annual emissions. And on Monday, a federal trial court in Indianapolis sided with the D.C. Circuit.

Spitzer, who said he would challenge the rules in court if the administration presses ahead, said the bulk of recent legal decisions buttress the argument that regulators should scrutinize plants' annual emissions. "We think the overwhelming weight of the law is on our side," he said.

But utilities lobbyist Scott Segal defended the hourly standard, saying that in light of recent court rulings "there is an emerging consensus that is hostile to the simplistic annual standard as the basis for triggering New Source Review."