Maine’s ethics panel on Wednesday fined a national anti-gay marriage group more than $50,000 and ordered it to file a campaign finance report that would reveal the donors behind the 2009 repeal of the state’s gay marriage law after finding that it violating Maine’s campaign finance laws.

The panel ruled that the National Organization for Marriage failed to properly register as a ballot question committee and file campaign finance reports in the referendum that struck down same-sex marriage before it was legalized by voters in 2012.

The decision could force the group to eventually disclose the names of its donors, which it has long sought to keep secret. But a lawyer for the National Organization for Marriage said it intends to appeal the decision in state court, and members of the Maine Ethics Commission said they expect litigation to continue for at least a year.

Groups must register as a ballot question committee and disclose contributors and expenditures if they raise or spend more than $5,000 to influence a state ballot question. The National Organization for Marriage gave nearly $2 million to Stand for Marriage Maine for the 2009 referendum, or more than 60 percent of the political action committee’s expenditures, state ethics investigators said in a report released earlier this month.

Investigators found that the national group "intentionally set up its fundraising strategy to avoid disclosure laws" by not allowing donors to designate that the funds were to be used to defeat same-sex marriage in Maine. The central role the group played in the campaign without disclosing who was behind the effort was a "significant violation of the law," they said.

Walt McKee, chairman of the ethics panel, said not accepting investigator’s recommendation that the group be fined would amount to "accepting a mockery" of Maine’s disclosure laws.

The group, which fought in Maine courts for more than four years to keep the names of its donors concealed, argues that it worked to ensure it was complying with Maine law by not raising any money specifically earmarked to influence the gay marriage question in the state. It says revealing the names will put its contributors at risk for harassment and intimidation and will chill future donations.

"We didn’t create a scheme, we tried to follow the law," Brian Brown, president of the Washington, D.C.-based organization, told the four-member panel on Wednesday.

Brown, who served as executive director of the National Organization for Marriage in 2009, was one of three members of the committee that led the Stand for Marriage Maine PAC. Commissioners said his dual role and the fact that the national group controlled a majority of the PAC’s funds was problematic for its argument that the group did not explicitly influence the campaign.