Consequently, it doesn't want their power.
The Idaho Public Utilities Commission has sided with utilities, all but shutting down such developments since December 2010.
But FERC says Idaho regulators' rejection of Murphy Flat's contracts violated PURPA and must reverse course.
Ron Williams, Murphy Flat's attorney, didn't return a phone call seeking comment Wednesday on FERC's decision to take the matter to a federal judge.
Peter Richardson, another Boise-based attorney for renewable energy developers, said FERC's move marks a first in PURPA's 34-year history: Shouldering the burden of litigation against a state, rather than leaving it up to the private company.
"It is extraordinary," said Richardson, who regularly butts heads with the utilities. "I think FERC has lost patience with the Idaho commission."
FERC spokesman Craig Cano in Washington didn't return a phone call seeking comment Wednesday.
FERC's decision to go to court came on a 4-1 vote.
In his dissent, Commissioner Tony Clark said he'd prefer the panel leave litigating up to Murphy Flat Wind.
"The Commission has chosen to expend federal resources to defend the claims of a single wind developer," Clark wrote. "I would prefer to follow longstanding policy: The Commission makes a decision, but then allows the developer to fight its own fight."
Stephanie McCurdy, an Idaho Power spokeswoman, said Idaho's biggest utility is considering options, now that a federal judge will likely decide the fate of its disputed contracts with Murphy Flat.
"We're looking at it very closely and evaluating what the next steps might be," McCurdy said.