When you ask a “yes” or “no” question, the worst answer you can get is “maybe.”

That’s what a group of publicly financed legislative candidates got from the Maine ethics commission, and they are understandably frustrated. We don’t blame them.

The question they asked was this: Is it all right for candidates to spend Clean Elections Fund money on ads that discuss their positions on referendum questions, not just to promote the candidates themselves? The response: Go ahead and try, the commission said, and if there are complaints, we’ll rule on that.

That’s not good enough. These candidates are trying to comply with the law, and they deserved an answer. We also don’t think the line between what is and isn’t legal should be that hard to draw.

Candidates should not be able to pump public money into a referendum campaign, like this year’s people’s veto of the tax reform law, through ads that focus on the question itself. An ad that is primarily about the referendum question would be no more acceptable than a publicly financed campaign using its money to promote a different candidate in another district.

But no matter how they are financed, candidates have to be able to define themselves. In a primary between two Republicans, it would be unfair to let the privately financed candidate discuss his or her position on tax reformwhile the publicly financed opponent is silenced.

Sometimes associating a candidate with an issue is more about defining and promoting the candidate than the issue. While there should be some rules governing what a candidate can do with public money — such as prohibitions on hiring family members — those limits should be applied with a very light hand when they involve the content of the candidate’s message.

As long as the ads make clear that they are promoting the candidate and not the issue, they should be permitted, even with public money.

It’s a difficult question, and one on which reasonable people may disagree. But the candidates at least deserved an answer. The commission should have given them one.