WASHINGTON, D.C. (MAY 17) — A U.S. federal appeals court ruled that the Clean Air Act is too broad and too vague in the way it distinguishes between healthy and unhealthy levels of pollution, and gives the Environmental Protection Agency too much authority in enforcing stricter air-quality standards.

A three-judge panel of the U.S. Court of Appeals for the District of Columbia ruled on Friday that the EPA¹s setting of air pollution rules amounted to an “unconstitutional delegation of legislative power.’ The decision will require the landmark environmental law to be substantially rewritten and the EPA¹s bounds of authority redrawn.

“What EPA lacks is any determinate criterion for drawing lines,’ the court said. “It has failed to state intelligibly how much (pollution) is too much.’

The panel reinforced the fact that EPA must follow the law as written by Congress and cannot just implement its own open-ended policy preferences, as Section 109 of the Act allows. “The maximum stringency would send industry not just to the brink of ruin but hurtling over it, while the minimum stringency may be close to doing nothing at all,” the court said.

The ruling was a victory for the American Trucking Associations and other industry groups that filed suit against the EPA. The groups had said that complying with the standards would cost them $45 billion a year.

In a statement, the ATA hailed the decision as “a significant victory for the trucking industry and all Americans. Now we can go forward in working out sensible rules that protect both our air and our economy.”

The EPA issued a statement reinforcing the need for “the health protections embodied by the clean air standards and the science behind them.” It noted that the ruling “does not question the science and process conducted by EPA justifying the setting of new, more protective standards.”

The agency said it planned to recommend an appeal to the Justice Department. But if it loses in the courts, the EPA said it would then call on Congress to “preserve these protections.’

Judge David Tatel dissented, saying the majority had ignored more than 50 years of Supreme Court precedents on the delegation of congressional authority.

“The Clean Air Act has been on the books for decades, has been amended by Congress numerous times, and has been the subject of regular congressional oversight hearings,’ he said.