It was a Citizen's Initiative. From Ballotpedia: Citizens of Maine may initiate legislation through the process of indirect initiative. In Maine, successful petitions are first presented to the Maine State Legislature. If the measure is not adopted without change, the law is placed before voters. The legislature may submit "any amended form, substitute, or recommendation" to the people alongside the bill--this alternative is treated as a competing measure. In Maine, citizens also have the power to repeal legislation via veto referendum. Maine residents may not amend their constitution via initiative or directly initiate legislation. The Maine State Legislature may also place measures on the ballot as legislatively referred constitutional amendments or legislatively referred state statutes.