Clean Power Plan.
Coffman said the lawsuit seeks to establish whether the federal government has the power to usurp states' control over their power grids and limit carbon emissions from the states' energy economies. It was filed in the United States Court of Appeals for the District of Columbia.
"We’ve proven again and again that good environmental policy can be developed and implemented successfully by Coloradans, and within the bounds of the law. This rule fits neither description," Coffman said in a statement.
The suit also asks the court to put the Clean Power Plan's deadlines on hold.
Gov. John Hickenlooper, a Democrat, said in August that the state government will comply with the ruling despite Coffman's lawsuit.
Environmentalists called the suit "deeply unfortunate."
"Putting Colorado's families first means carrying out our nation's clean air laws and safeguarding the health of our children," Vickie Patton, general counsel for the Environmental Defense Fund, said in a statement.
As CPR News' Grace Hood reported in August when the plan was announced, it aims to curb carbon emissions in Colorado by 40 percent by 2030. And the state is well on its way to meeting that goal:
Stacy Tellinghuisen with the conservation group Western Resource Advocates estimates the state has already committed to meeting three-fourths of the final EPA goal.
"When we look at the state’s trajectory, we see a dramatic reduction in carbon pollution particularly from our coal plants between now and 2020,” said Tellinghuisen. “That’s not driven by these regulations. That’s been driven by these proactive measures that utilities and the state have taken."