[13] The apportionment of its legislative body and, only in connection with such action taken pursuant to this subparagraph, the composition and membership of such body, the terms of office of members thereof, the units of local government or other areas from which representatives are to be chosen and the voting powers of individual members of such legislative body. Except for the equal apportionment requirements in subclause (i.) of clause (a.) and clause (c.) of this subparagraph, which shall apply generally to any local government, the power granted by this subparagraph shall be in addition to and not in substitution for any other power and the provisions of this subparagraph shall apply only to local governments which adopt a plan of districting or redistricting thereunder.
[a] A plan of districting or redistricting adopted under this subparagraph shall comply with the following standards, which shall have priority in the order herein set forth, to the extent applicable:
(i) If such plan of districting or redistricting includes only single-member districts, such districts shall be as nearly equal in population as is practicable; the difference in population between the most and least populous district shall not exceed five percent of the mean population of all districts. If such plan of districting or redistricting includes multi-member districts, the plan shall provide substantially equal weight for the population of that local government in the allocation of representation in the local legislative body; and
(ii) Districts shall not be drawn with the intent or result of denying or abridging the equal opportunity of racial or language minority groups to participate in the political process or to diminish their ability to elect representatives of their choice; and
(iii) Districts shall consist of contiguous territory; and
(iv) Districts shall be as compact in form as practicable; and
(v) Districts shall not be drawn to discourage competition or for the purpose of favoring or disfavoring incumbents or other particular candidates or political parties. The maintenance of cores of existing districts, of pre-existing political subdivisions including cities, villages, and towns, and of communities of interest shall also be considered. To the extent practicable, no villages or cities or towns except those having more than forty percent of a full ratio for each district shall be divided; and
(vi) Districts shall be formed so as to promote the orderly and efficient administration of elections.
[b] A plan of districting or redistricting adopted by a county under this subparagraph may provide that mayors of cities or villages, supervisors of towns or members of the legislative bodies of cities, towns, or villages, who reside in the county shall be eligible to be elected as members of the county legislative body.
[c] As used in this subparagraph the term “population” shall mean residents, citizens, or registered voters. For such purposes, no person shall be deemed to have gained or lost a residence, or to have become a resident of a local government, as defined in subdivision eight of section two of this chapter, by reason of being subject to the jurisdiction of the department of corrections and community supervision and present in a state correctional facility pursuant to such jurisdiction. A population base for such a plan of apportionment shall utilize the latest statistical information obtainable from an official enumeration done at the same time for all the residents, citizens, or registered voters of the local government. Such a plan may allocate, by extrapolation or any other rational method, such latest statistical information to representation areas or units of local government, provided that any plan containing such an allocation shall have annexed thereto as an appendix, a detailed explanation of the allocation.
[d] Where a public hearing on a local law proposed to be adopted under this subparagraph is required, by subdivision five of section twenty of this chapter, to be held only before an elective chief executive officer, the legislative body shall not adopt such proposed local law until after a public hearing shall have been held thereon before it, on notice as provided in such subdivision five, in which event no public hearing thereon before such chief executive officer shall be required.
[e] A local law proposed to be adopted under this subparagraph shall be subject to referendum only in the manner provided by paragraph j of subdivision two of section twenty-four of this chapter, except that such local law shall be subject to a mandatory referendum in any county in which a provision of law requires a mandatory referendum if a local law proposes a change in the form or composition of the elective governing body of the county. The local law may be so structured as to permit separate submission of the principle elements (such as, multiple office holding as in clause (b) above, the use of multiple member or floterial districts in portions of the local government, and so forth) of the plan and also may provide alternatives in the event one or more of these separate submissions is rejected by the electorate.
[f] Notwithstanding any inconsistent provisions of any general or special law, or any local law, ordinance, resolution or city or county charter heretofore or hereafter adopted, no local government may restructure its local legislative body (pursuant to provision of this chapter or any other provision of law) more than once in each decade commencing with the year nineteen hundred seventy; provided, however, that this prohibition shall not prevent the periodic adjustment of the weight of the votes of representatives on the basis of current census, voter, or other valid information where an existing plan distributes the votes of representatives on such a basis.
