AUGUSTA, Maine — A Washington, D.C.-based organization under investigation for its financial role in the campaign to repeal Maine’s gay marriage law has fired back with a lawsuit questioning the constitutionality of a state election law.

The National Organization for Marriage is the largest contributor to the Question 1 ballot initiative, which seeks to overturn Maine’s same-sex marriage law. As of the end of September, the organization had funneled more than $500,000 to Stand for Marriage Maine, which supports the repeal.

Click the play button below to listen to reporter Kevin Miller talk about the Question 1 campaign on Public Radio International’s To the Point with Warren Olney. Miller’s segment starts at 23:24.

Earlier this month, the Maine Ethics Commission directed staff to determine whether NOM was skirting campaign finance laws in order to avoid disclosing the identities of contributors.

Now, the organization has filed a lawsuit in U.S. District Court in Bangor alleging that Maine’s financial reporting requirements are unconstitutional.

The lawsuit seeks a court injunction prohibiting the state from enforcing a law that NOM officials claim is being used to harass and intimidate opponents of gay marriage.

“The reporting requirements become onerous and burdensome, especially when you are working in several states, and are an infringement of free speech,” said Brian Brown, NOM’s executive director.

Ethics Commission officials declined to comment on the specific case but defended the law, which requires organizations soliciting more than $5,000 for a ballot question campaign to file financial disclosure reports with the state.

“The ‘ballot question committee’ system is very important to the public’s understanding of who is influencing these elections in Maine,” said Jonathan Wayne, executive director of the Ethics Commission.

The National Organization for Marriage came to prominence last year when it helped overturn a gay marriage law at the ballot box in California. Critics questioned the group’s fundraising techniques.

One of those critics, Fred Karger with the organization Californians Against Hate, filed a complaint with the Maine Ethics Commission earlier this year. Karger alleges that NOM was essentially “money laundering” by soliciting donations from opponents of same-sex marriage for the Maine campaign, all the while promising those donors their identities would remain confidential.

Under the state’s rules governing ballot question committees, which are different from political action committees, anyone who donates more than $100 would have to be identified in campaign finance reports.

The Ethics Commission went against the staff recommendation and voted 3-2 to order an investigation.

Brown and NOM’s attorneys contend the organization did not violate Maine’s rules because they were soliciting donations for the general fight to protect “traditional marriage,” not for the Maine campaign in particular.

Brown argued in an interview Thursday that the reporting requirements — which include registering as a ballot question committee, appointing a treasurer and keeping detailed records for four years — are an undue burden. He also described Maine’s law as legally unclear and “patently unconstitutional” because it prohibited or discouraged free speech in the form of advocacy on one side of an issue.

He also accused the Ethics Commission members and Karger of waging a politically motivated “witch hunt,” despite the fact that the vote to order an investigation was bipartisan.

“What we are basically doing is filing a lawsuit to make clear our First Amendment rights to free speech,” Brown said. He also said that some donors to NOM during the California campaign later were harassed and threatened.

Wayne said the law is set up to ensure transparency in the election system.

“In the past couple of decades, a lot of important issues have come before voters as statewide ballot initiatives, including environmental issues, gambling, tax and spending limitations and hunting practices,” Wayne said.

“It’s common for national groups to want to get involved in these elections … and it is important for Maine voters to know who is attempting to influence these state laws,” Wayne said.