AUGUSTA — Maine’s campaign finance watchdog voted Wednesday to seek a legal opinion on a controversial campaign tactic that three Democratic candidates for governor have used on their websites.

The Maine Commission on Governmental Ethics & Election Practices voted 4-0 to ask the Office of the Maine Attorney General to weigh in on “red boxing,” which is when candidates use explicit language on their websites that could be used to direct advertising spending.

Commission staff have taken the opinion that red boxing itself is not illegal, but have raised concerns that it could lead to illegal spending. Candidates are not allowed to coordinate with outside groups, and contributions to candidates are limited under state law. The limit for individual spending on the governor’s race is $2,075 per election.

Commission Chair William Schneider said Wednesday that it’s unlikely the body would pursue any action against the three Democrats, and indicated the commission will probably seek to issue an advisory opinion for candidates after they’ve received the legal advice.

“We’re not at all interested in trampling on anybody’s free speech,” he said. “I think the point we probably want to make is a candidate is stepping into risky territory if they openly request a third party to make expenditures on their behalf.”

James Kilbreth, an attorney and former assistant attorney general, recently complained to the commission about Democrat Nirav Shah’s use of red boxing. In his complaint, Kilbreth said the practice “seems to be a blatant violation of the prohibition against candidate coordination with dark money ‘independent expenditure’ PACs.”

Shah’s campaign in turn asked the commission to look into use of the practice by the campaigns of Hannah Pingree and Troy Jackson, two of his opponents in the primary.

Newell Augur, an attorney for Shah, wrote to the commission this week saying that red boxing has been used in previous election cycles in Maine, and is legal under state election law.

“A decision to the contrary puts the Ethics Commission in the near impossible and undoubtedly dangerous position of regulating not only the political content of campaign websites but the individual speech of candidates,” Augur wrote.

The language used in red boxing goes beyond simply stating a candidate’s policy views, and includes detailed directions on themes, target audiences and types of media for prospective advertising. This information is often put in a red box on a candidate’s website, according to information from commission staff.

Kate Knox, an attorney with the Pingree campaign, urged the commission to seek the legal opinion at Wednesday’s meeting. She said it could be hard for the commission to prove a link between outside spending and the messaging on campaign websites, and also raised free speech concerns. Ultimately, though, Knox said the Pingree campaign has taken down its red box and will comply with the advisory opinion the commission eventually issues.

A representative of the Jackson campaign, Robin Logsdon, was also at Wednesday’s meeting.

“Whatever rule the commission comes up with, I think it would be useful to think through framing it in such a way that normal campaign speech doesn’t become a violation,” he said.

Maine Citizens for Clean Elections, a nonpartisan group that works to ensure Maine’s campaign finance laws and elections are serving the public interest, has urged the commission to issue guidance prohibiting red boxing. In a memo to the commission, the group said that red boxing “is materially different” from ordinary candidate speech and risks violating contribution limits.

“If it looks like a duck, quacks like a duck and comes with a media-buy schedule, the commission does not have to call it a swan,” the group wrote.