Me. Const. art. IV, pt. 2, § 2

The Legislature which shall convene in the year 2013, and also the Legislature which shall convene in the year 2021 and every tenth year thereafter, shall cause the State to be divided into districts for the choice of a Senator from each district, using the same method as provided in Article IV, Part First, Section 2 for apportionment of Representative Districts.

The apportionment plan of the commission established under Article IV, Part Third, Section 1-A shall be submitted to the Secretary of the Senate no later than June 1st of the year in which apportionment is required. In the preparation of legislation implementing the plan, the commission, following a unanimous decision by commission members, may adjust errors and inconsistencies in accordance with the standards set forth in this Constitution, so long as substantive changes are not made. The Legislature shall enact the submitted plan of the commission or a plan of its own by a vote of 2/3 of the Members of each House by June 11th of the year in which apportionment is required. Such action shall be subject to the Governor's approval as provided in Article IV, Part Third, Section 2.

In the event that the Legislature shall fail to make an apportionment by June 11th, the Supreme Judicial Court shall, within 60 days following the period in which the Legislature is required to act but fails to do so, make the apportionment. In making such apportionment, the Supreme Judicial Court shall take into consideration plans and briefs filed by the public with the court during the first 30 days of the period in which the court is required to apportion.

The Supreme Judicial Court shall have original jurisdiction to hear any challenge to an apportionment law enacted by the Legislature, as registered by any citizen or group thereof. If any challenge is sustained, the Supreme Judicial Court shall make the apportionment.