A sign protesting the proposed Central Maine Power corridor is seen in a Jackman lawn on May 29. Stop the Corridor, the group that paid for the signs, is suing the state's campaign finance regulator in a bid to shield its donors from public view. Credit: Natalie Williams / BDN

A group opposing the proposed Central Maine Power corridor is suing Maine’s campaign finance regulator in an attempt to stop an investigation that could reveal its secret funding sources ahead of the November referendum on the hydropower corridor.

The Maine Ethics Commission voted last month to require Stop the Corridor to disclose its financial information to the commission so it can determine whether the group should have been required to register as a political committee. If it makes that decision, the nonprofit’s donors would have to be disclosed under state campaign finance laws.

The lawsuit, filed in Cumberland County Superior Court on June 19, argues that the commission does not have the jurisdiction to investigate the anti-corridor group’s finances. It is the latest legal challenge in an ongoing fight over the $1 billion energy corridor which would bring hydropower from Canada to the regional grid through western Maine.

The ethics investigation into Stop the Corridor stems from a complaint filed by Clean Energy Matters, a CMP-affiliated political committee supportive of the corridor project. The lawsuit alleges that the ethics commission does not have the grounds to investigate because Clean Energy Matters did not show “sufficient grounds for believing that a violation may have occurred” as required by state law.

The suit argues that the commission cannot investigate whether Stop the Corridor should be required to register as a ballot question committee because Clean Energy Matters only alleged that the group should be required to register as a political action committee, a distinct entity with different registration requirements.

Under state law, a group that receives or spends more than $1,500 to influence a ballot question is required to formally register as a committee. Stop the Corridor gave more than $85,000 in in-kind contributions to No CMP Corridor, one of the groups actively supporting the referendum, according to state data.

In an ethics hearing earlier this year, the group declined to say how it raised the money, but argued that it is working to stop the corridor through the permitting process, not the electoral process.

However, the anti-corridor group spent more than $1 million on TV and Facebook ads as of earlier this year. As a 501(c)(4) nonprofit, it is not required to disclose its donors as long as politics is not its primary purpose. It would be required to if the ethics commission determined that it was acting as a ballot question committee.

In a Tuesday release, Clean Energy Matters Executive Director Jon Breed decried the lawsuit, saying it was “making a mockery of Maine’s election laws.”

Stop the Corridor’s lawsuit is the latest of several legal challenges related to the November referendum on the CMP corridor. In May, Maine’s high court ruled that the referendum could proceed despite a challenge from Clean Energy Matters, which argued that a person who notarized signatures for the referendum had improperly provided other services to the anti-corridor campaign.

Shortly afterward, CMP’s parent company sued, arguing that the referendum was unconstitutional. That suit is still pending, though Secretary of State Matt Dunlap said earlier this month that, although the referendum may be unconstitutional, it should proceed anyway.