Maine’s highest court heard arguments Wednesday about whether the secretary of state should split the multipart referendum opposing Central Maine Power’s transmission line project into three separate questions on the November ballot.

A lawsuit filed by Rep. Christopher Caiazzo, D-Scarborough, contends that the November ballot question contains three distinct issues that voters should decide separately. Specifically, the question asks whether voters want to prohibit “high impact transmission lines” in part of western Maine, whether similar projects statewide should require legislative approval, and whether lease agreements through Maine’s public lands should require a two-thirds vote from the Legislature.

The lawsuit is the latest legal action surrounding New England Clean Energy Connect’s controversial 145-mile, high-voltage transmission line to enable Hydro-Quebec to sell renewable energy to Massachusetts. Opponents who have been unable to stop the project either at the permitting stage or through the Legislature are hoping to block it at the ballot box even as crews have begun work on the corridor.

In Wednesday’s oral arguments, Caiazzo’s attorney said Maine Secretary of State Shenna Bellows failed to follow the law when she grouped the three items together in a single ballot question.

“(The law) guarantees voters the right to consider each issue on its own merits,” attorney Joshua Dunlap told the justices. “This right facilitates the people’s exercise of  their legislative powers. It prevents logrolling by ensuring that separate issues cannot be wrapped into a single bill without permitting separate votes.”

But an attorney for Bellows’ office called Maine’s statute unambiguous when it it refers to the “proper suggested format” –  not a mandatory format – of breaking up multi-issue initiatives into separate questions. In other words, it is up to the petitioners to decide whether to submit multiple questions.

“That phrase has only one possible meaning: that the format is non-mandatory,” Jonathan Bolton told the justices. “No other definition of ‘suggested’ makes any sense given the syntax of the phrase and ordinary English usage.”

As written by Bellows’ office, the ballot question reads:

“Do you want to ban the construction of high impact electric transmission lines in the Upper Kennebec Region and to require the Legislature to approve all other such projects anywhere in Maine, both retroactively to 2020, and to require the Legislature, retroactively to 2014, to approve by a two-thirds vote such projects using public land?”

Supporters of the New England Clean Energy Connect project say it will help address the region’s climate-related goals by pumping 1,200 megawatts of renewable energy into the New England power grid, displacing generation from fossil fuels. Opponents argue regulators have failed to assess the full environmental impact of a project they claim will scar the landscape of western Maine and disrupt wildlife.

Maine’s Supreme Judicial Court has given Caiazzo’s lawsuit a higher priority because the wording issue must be settled by Aug. 27 in order to allow the Secretary of State’s Office time to have ballots printed and distributed ahead of the November election.

While questioning attorneys on Wednesday, justices suggested that splitting up the question could run counter to the intent of the people who proposed the referendum and gathered the signatures needed to place it on the ballot.

Justice Joseph Jabar said that unlike legislators, who have the opportunity to change the language of bills in work sessions or on the floor of the House, voters can’t amend a bill that comes to them through the citizen-initiative process. And the petitioners behind the ballot question take a chance by only offering voters a single, all-or-nothing question.

“That’s a decision they made when the formed the petition,” Jabar told Dunlap. “Isn’t that what the vote should be on? An all-or-nothing – you either take the whole package or none of it?”

An attorney for one of the leading proponents of the ballot initiative, former lawmaker Tom Saviello, agreed that a multi-question initiative is not what the proponents had in mind.

“The intent was to present it as one package and to have it voted on in its entirety,” attorney Jeana McCormick said.

Caiazzo filed his lawsuit on June 3, asking the Cumberland County Superior Court to direct Bellows to break the single question into three separate questions.

A month later, that court rejected Caiazzo’s request on grounds that the statute instructs the secretary of state to “advise petitioners” that a single question per issue was the “proper suggested format.” The court seized on the word “suggested” in that phrase, saying the “the most sensible reading” is that it is non-mandatory.

“Clearly, if the Legislature wished to direct the secretary to split ballot questions by issue, instead of only advising petitioners of the suggested format for ballot questions, it knew how to do so,” the court wrote.

In their appeal to the Supreme Judicial Court, Dunlap and Caiazzo’s other attorneys from the firm Pierce Atwood stated that grouping the three issues into one question “disenfranchises voters by subjecting them to logrolling.”

“A voter would reasonably have different opinions on these three parts of the initiative; having more than one question would help voters better understand the legal changes wrought by the initiative; and the initiative’s three major provisions are severable and can be enacted or rejected separately without negating the proponent’s intent to stop construction of the NECEC,” they wrote in a brief filed with the Law Court.

Bellows’ legal team countered in their brief that none of the 65 citizen-initiated ballot initiatives in Maine’s history have ever been split into multiple questions.

“It does not compel the secretary to split initiatives into multiple questions against the petitioners’ wishes,” they wrote.

They also gave examples of initiatives that involved multiple proposals. Those included the 2016 marijuana legalization ballot initiative allowing possession but also production, sale and distribution of the drug, and a 2011 referendum asking voters whether they supported authorizing two different slot machine operations at opposite ends of the state.

Supporters and opponents of the CMP-backed corridor project already have spent more than $15 million ahead of the November ballot question. More than $13 million of that has been spent by two political action committees largely bankrolled by CMP and Hydro-Quebec.

Opponents of the New England Clean Energy Connect project had hoped to block the project at the ballot box last year but failed to put the issue before voters. In that case, the Maine Supreme Judicial Court ruled that the proposed initiative was unconstitutional because it would have reversed the Maine Public Utilities Commission’s approval of the project.

Lawmakers debated and passed several bills linked directly or indirectly to the corridor issue this year only to have them vetoed by Gov. Janet Mills, who supports the project.

In the final hours of the special session that wrapped up on Monday, both the House and the Senate passed a resolution saying the Mills administration should have received legislative approval for leases allowing the NECEC corridor to pass through state-owned public reserved lands in West Forks Plantation and in Johnston Mountain Township.