With credit to Christopher Cousins and Michael Shepherd at the Bangor Daily News, here is our version of the timeline:
March, 2001: Ranked choice voting is introduced in the Maine State Legislature for the first time as LD 1714.
2003 - 2013: Bills for ranked choice voting are introduced in each new Legislature.
2008: League of Women Voters of Maine opens a League study on ranked choice voting, also called instant run-off voting.
June 3, 2009: The Maine Legislature kills a bill sponsored by then-Rep. Diane Russell, D-Portland, that would have established a ranked-choice voting pilot project in several Maine municipalities.
March 7, 2011: After a three-year study, the League of Women Voters issues a position statement endorsing ranked-choice voting in single-seat elections.
June 11, 2013: A bill to establish a ranked-choice voting system in state elections from then-Sen. Dick Woodbury, I-Yarmouth, fails after 90-57 and 20-13 votes against it in the House of Representatives and Senate, respectively. Read "our testimony on LD 518."+files/LD_518_860_Ranked_Choice_Voting.pdf>
Summer 2013: The League of Women Voters of Maine convenes a working group on ranked choice voting with participants including legislators, lawyers, local and national advocates, and interested citizens.
February 2014: The League of Women Voters of Maine hosts a moot court on the constitutionality of ranked choice voting.
October 2015: Advocates led by Dick Woodbury, Diane Russell launch the petition drive to put a citizen initiated question on the ballot for ranked choice voting. They eventually form the Committee for Ranked Choice Voting.
January 2016: Secretary of State Matthew Dunlap and Attorney General Janet Mills, both Democrats, flag what they see as constitutional issues with a citizen-initiated proposal to implement ranked-choice voting.
November 2016: Following a citizen-initiated petition to put the question on the ballots, approximately 52 percent of Maine voters approve implementing ranked-choice voting for gubernatorial, congressional and legislative races. Read the League's media release.
February 2017: The Maine Senate votes 24-10 to ask the Maine Supreme Judicial Court to develop and issue an opinion on the constitutionality of ranked-choice voting.
May 2017: The Maine Supreme Judicial Court releases an advisory opinion that part of the ranked-choice voting law is unconstitutional because of a reference in the Maine Constitution referring to elections being won by pluralities, which means whoever receives the most votes. The 44-page decision was unanimous. Here is the League's brief. You can find all the court documents here at the web site of the State of Maine Judicial Branch.
Oct. 24, 2017: After months of debate about bills to repeal or continue ranked-choice voting that resulted in partisan gridlock, the Legislature enacts a bill that put off the implementation of ranked-choice voting until the Maine Constitution can be amended to accommodate it. The bill includes a provision that would nullify ranked-choice voting if that doesn't happen prior to December 2021.
November, 2017: The Committee for Ranked Choice Voting launches a people's veto campaign to repeal the bill that put off implementation of RCV. The League endorsed the people's veto campaign.
March 5, 2018: A people's veto petition seeking to nullify the Legislature's law to delay implementation is certified by Secretary of State Matthew Dunlap.That sets the stage for ranked-choice voting to be implemented in time for the June 12, 2018, primary election, but also sets up a referendum in that election to repeal the law passed by the Legislature in October 2017.
March 29, 2018: Secretary of State Matthew Dunlap drops a bombshell when he announces that a legislative committee analyst found a discrepancy in current Maine law that calls for a plurality to win in one place and a ranked-choice majority in another. Dunlap says that because of deadlines to print and deliver ballots, he will move forward with implementation.
April 2, 2018: Following a contentious debate, the Maine Senate votes to authorize Senate President Mike Thibodeau the temporary authority to intervene legally in current and future suits involving ranked-choice voting.
April 3, 2018: On behalf of the Senate, Maine Senate President Mike Thibodeau files court papers requesting " expedited review by the Maine Supreme Judicial Court" of potential constitutional problems with the ranked-choice voting law before the June 12, 2018, elections.
April 4, 2018: Maine Superior Court Justice Michaela Murphy issues a temporary injunction ordering Secretary of State Matthew Dunlap to move ahead with implementation of ranked-choice voting for the June 12, 2018, elections. Proponents of the system and eight gubernatorial candidates had sought the ruling.
April 11, 2018: Maine Superior Court Justice Michaela Murphy formally asks the Maine Supreme Judicial Court to rule on seven questions related to the Maine Senate's petition to the courts.
April 12, 2018: The Maine Supreme Judicial Court meets to hear new arguments on the constitutionality of ranked-choice voting. The League of Women Voters of Maine filed an amicus brief in that case.
April 17, 2018: The Court rules that "...ranked-choice voting is the law of Maine with regard to the primary elections on June 12, 2018,..." Read the final opinion.
May 4, 2018: The the Maine GOP filed a last-minute federal lawsuit to prevent ranked choice voting from being used in the Republican primary elections on June 12, 2018. Here's the original GOP complaint. Read the League's statement on the lawsuit.
May 29, 2018: A federal judge denied the GOP request for an injunction blocking RCV in the GOP primaries. And here's the federal court ruling.
June 12, 2018: The people's veto on RCV prevails at the polls with about a 54% majority. This means that RCV will be used in the general elections for federal office beginning in November, 2018, and in primary elections for state and federal office going forward.
June 14, 2018: Ballots begin arriving in Augusta from around the state for the first central RCV count in Maine. Contests to be decided by RCV include the Democratic nominates for governor and for U.S. Congress in the 2nd District.
The Maine State Law Library has compiled an excellent timeline tracing the recent history of ranked choice voting in Maine.