SECTION l. Chapter 503 of the acts of 1952, as most recently amended by chapter 94 of the acts of 2019, is hereby amended by inserting after section 8 the following section:-

Section 8A. (a) For the purposes of this section, the following terms shall, unless the context clearly requires otherwise, have the following meanings:

“Batch elimination”, the simultaneous defeat of multiple candidates for whom it is mathematically impossible to be elected.

“Concluded ballot”, a ballot that does not rank any continuing candidate, contains an overvote at the highest-ranked continuing candidate, or contains 2 or more sequential skipped rankings before its highest-ranked continuing candidate.

“Continuing candidate”, a candidate who has not been defeated or elected.

“Highest-ranked continuing candidate”, the continuing candidate with the highest ranking on a voter's ballot.

“Last-place candidate”, (i) the candidate with the lowest vote total in a round of the ranked-choice voting tabulation; or (ii) a candidate that is defeated in batch elimination.

“Overvote”, a circumstance in which a voter ranks more than 1 candidate at the same ranking.

“Ranked choice voting”, a method of casting and tabulating ballots in which voters rank candidates for office in order of preference.

“Ranking”, the number assigned on a ballot by a voter to a candidate to express the voter's preference for that candidate. Ranking number 1 shall be the highest ranking, ranking number 2 shall be the next-highest ranking and so on.

“Round”, an instance of the sequence of voting tabulation steps established pursuant to subsection (c).

“Skipped ranking”, a circumstance in which a voter does not use a ranking and ranks a candidate with a subsequent ranking.

(b) The offices of select board member, school committee member, town clerk, moderator, elected member of the board of the housing authority and assessor shall be elected by ranked choice voting at the annual election. Ranked choice voting shall apply to a single-seat office only when the number of candidates exceeds 2 and to a multi-seat office only when the number of candidates exceeds the number of seats to be elected. Ranked choice voting elections shall be tabulated pursuant to this section.

(c) In any single-seat election, each round shall begin by counting the number of votes for each continuing candidate. Each ballot shall count as 1 vote for its highest-ranked continuing candidate. Concluded ballots shall not be counted for any continuing candidate. Each round shall end with 1 of the following 2 outcomes:

(1) If there are more than 2 continuing candidates, the last-place candidate shall be defeated or the last-place candidates shall be defeated in batch elimination, and a new round shall begin; or

(2) If there are 2 continuing candidates, the candidate with the fewest votes shall be defeated and the candidate with the most votes shall be elected, and tabulation shall be complete.

(d) In any multi-seat election, the first seat shall be filled pursuant to the tabulation process established in subsection (c). The remaining seats shall be filled by repeated application of the tabulation process in established in subsection (c); provided, however, that all votes marked for candidates who have already been elected shall be disregarded and votes shall  be counted for the next highest-ranked continuing candidate.

(e) A candidate shall be defeated in batch elimination if:

(1) the candidate's current vote total plus all votes that could possibly be transferred to the candidate in future rounds is not enough to equal or surpass the candidate with the next higher current vote total; or

(2) the candidate has fewer votes than a candidate described in clause (1).

(f) If 2 or more last-place candidates are tied and batch elimination does not apply, the candidate with the fewest votes in the prior round shall be defeated. If 2 or more such tied candidates were tied in the prior round, the second tie shall be decided by referring similarly to the standing of the candidates, in terms of votes, in the second-prior round. This process shall be applied successively as many times as necessary, a tie shown in any prior round shall be decided by referring to the standing of the candidates in the round immediately preceding the tie.

(g) The town clerk may make any changes to the ranked choice voting ballot and tabulation process necessary to ensure the integrity and smooth functioning of the election; provided, that ranked choice voting shall still be used and the fewest number of changes are made to achieve such purpose.

(h) The town clerk shall publish election results that show the tabulations by rounds.

SECTION 2. This act shall take effect upon the acceptance by the town of Arlington by the affirmative vote of a majority of voters at any regular or special election at which the question of acceptance is placed on the ballot.