Five years ago, the leading national opponent of same-sex marriage helped fund and promote a successful referendum to repeal a Maine law allowing gay couples to wed.

But that 2009 people’s veto was the last victory in Maine for the National Organization for Marriage. Maine voters have since made gay marriage legal, and federal and state courts have rejected the organization’s arguments for keeping the names of its donors confidential.

Now state investigators are recommending that Maine’s ethics commission fine the organization a record $50,250 and require it to register with the state as a ballot committee and identify major funders.

This is a chance to advance open government and citizen engagement. For voters to have the quality information they need to make a decision, those spending money to influence election results should have to stand behind their donations, not hide them.

The National Organization for Marriage was the chief organizer of and biggest contributor to the 2009 campaign against gay marriage, supplying about two-thirds of the $3 million spent by gay-marriage opponents. The organization sent out frequent messages highlighting the importance of donations to defeat gay marriage. And these action alerts worked, a state report found: The group’s largest contributor in 2009 gave more than $2.4 million, $200,000 of which was earmarked for the Maine people’s veto.

But the National Organization for Marriage failed to follow some basic state mandates for participation in the people’s veto process: It didn’t register as a ballot question committee, and it didn’t report on its fundraising. In order to keep its donors’ names secret, the organization has cited its status as a nonprofit “social welfare” organization and the need to protect its supporters from reprisals and harassment. Neither argument holds up.

Internal Revenue Service rules for 501(c)(4) groups don’t exempt nonprofits that engage in electioneering from having to follow state election disclosure laws. In fact, state district courts have said as much in rulings requiring nonprofit groups to reveal the identity of donors to referendums in Idaho and Montana.

The idea that donors to the National Organization for Marriage would be at risk if their names were revealed is rooted in a 1958 Supreme Court ruling that upheld the right of the NAACP in Alabama to keep its membership list private. At that time, those in the NAACP couldn’t count on police protection from physical and verbal threats. The parallel between those embattled civil rights activists and wealthy donors to nonprofit organizations is hardly apparent.

Participation in democracy isn’t for the faint of heart. Making your views known means that you’ll face criticism, arguments and ridicule. For our political process to function at its best, anyone who openly expresses an opinion should have to answer to it — regardless of how much money they have in their bank account.