North Dakota and some of the state's major energy interests filed a federal lawsuit Wednesday seeking to overturn a 2007 Minnesota law that restricts power companies from importing electricity from new coal-fired power plants in other states.

The lawsuit, filed by that state's attorney general, two coal companies, their trade association and three electric cooperatives, alleges that the Minnesota law violates the U.S. Constitution by unfairly restricting interstate commerce.

It brings to a head a long-simmering dispute between the two state governments over fossil fuels and greenhouse gas emissions.

Minnesota's law bans new fossil-fuel power plants in Minnesota and restricts imports of electricity from new fossil-fuel plants in other states by requiring the utilities to offset the carbon dioxide emissions with reductions elsewhere.

North Dakota, which has deposits of lignite coal, wants to build at least three more coal-fired power plants and sell electricity in neighbor states. Those projects have been stymied by carbon-reduction requirements of the 2007 Next Generation Energy Act, the lawsuit says.

The lawsuit asserts that Minnesota's law is "purely a symbolic gesture that could only have a negligible impact toward actually achieving the purpose of reducing greenhouse gases on a global scale."

It further alleges that Minnesota lawmakers carved out exemptions for certain power plants and for mining and steel carbon emitters.

"While an operating plant in Minnesota gets an exemption, we have to jump through these hoops," North Dakota Attorney General Wayne Stenehjem said in an interview.

Katharine Tinucci, a spokeswoman for Gov. Mark Dayton, said the lawsuit has no merit. The three Minnesota government agencies named as defendants had no specific responses to the suit's allegations.

Environmental lawyer Beth Goodpaster said the lawsuit shows a misunderstanding of the law, which applies equally to Minnesota and out-of-state coal power plants. She said one of the coal power plants exempted from the law -- and cited in the lawsuit -- was built in North Dakota.

"It does not on its face, or as applied, discriminate against out-of-state interests," said Goodpaster, director of the clean energy program for the Minnesota Center for Environmental Advocacy, a St. Paul based nonprofit that focuses on environmental law.

A veto from Dayton

The Minnesota Legislature passed a bill this year to repeal the carbon provisions, but Dayton vetoed it, saying coal-fired electricity poses "unacceptable risks to human health and to our climate."

The suit was filed in U.S. District Court in Minnesota on behalf of the Industrial Commission of North Dakota, a state oversight body made up of the attorney general, governor, agriculture commissioner and private interests.

The other plaintiffs are the Lignite Energy Council, North American Coal Corp., Great Northern Properties Ltd., Basin Electric Power Cooperative, Missouri River Energy Services and Minnkota Power Cooperative. Minnkota serves customers in both states.

Stenehjem, the North Dakota attorney general, said the state's seven lignite power plants have invested more than $1 billion in pollution controls.

"We are good stewards of our environment," he said. "With all respect to regulators in Minnesota, we love our environment more than they do."

David Shaffer • 612-673-7090