Kansas City, Mo. ? An appeals court Tuesday overturned the state’s 2005 approval of Kansas City Power & Light Co.’s plan to build a second coal-fired plant in northwest Missouri.

The Missouri Court of Appeals for the Western District ruled that the Public Service Commission failed to follow state law for evaluating new power plants and didn’t have jurisdiction to approve KCP&L’s request.

It’s unknown whether the decision will force the utility to halt construction of the plant being built 25 miles northwest of Kansas City.

Tom Robinson, a spokesman for KCP&L’s parent company, Great Plains Energy Inc., said the ruling only faulted how the commission approved the company’s $1.3 billion long-range regulatory plan, which includes the Iatan 2 plant, wind farms in Kansas and upgraded pollution controls at existing plants.

“It does not address the merits of the components of our comprehensive energy plan,” Robinson said.

But the company’s critics, who say the coal-fired plant will worsen pollution, said the decision was a major setback for KCP&L.

“This plant is dinosaur technology,” said Henry Robertson of Great Rivers Environmental Law Center, which represented the Sierra Club and Concerned Citizens of Platte County in challenging the commission’s decision. “KCPL may have to rethink whether they’re going to continue building it.”

KCP&L already operates a coal-fired plant at the site near Weston, called Iatan 1.

The company developed its long-range plan in 2004 after a series of commission-sponsored meetings to review the company’s future power needs, costs and environmental requirements. At the end of the meetings, state officials, the company and a number of its largest customers presented the commission with the long-range plan, including Iatan 2 and restrictions on when the company could raise electric rates.

In typical cases, the appeals court noted, a utility would propose building the plant or raising rates and then later work out a compromise with its customers and regulators.

KCP&L said it wanted to avoid a long, drawn-out approval process that could have affected its investment rating.

Commissioners approved the compromise on July 28, 2005.

Opponents filed suit, saying commissioners essentially conducted the case backward and hamstrung public comment on the plan, an argument the three-judge appellate panel supported.

“The procedures set forth in the statutes provide the mechanism for prosecuting substantive rights and must be followed,” the court said, adding that the commission lacked authority to waive its rules.

Commission spokesman Gregg Ochoa said the commission had no comment.

“I don’t know if the commissioners have even seen it,” Ochoa said.

The plant’s critics welcomed the decision.

“We are ecstatic,” said Melissa Hope of the Missouri Sierra Club. “KCP&L tried to do something outside of the public process to gain approval to build an expensive and dirty coal-burning power plant.”