How Instant Runoff Voting Works
Instant runoff voting allows voters to rank candidates in order of preference (i.e. first, second, third, fourth and so on). Voters have the option to rank as many or as few candidates as they wish, but can vote without fear that ranking less favored candidates will harm the chances of their most preferred candidates. First choices are then tabulated. If more than two candidates receive votes, a series of runoffs are simulated, using voters' preferences as indicated on their ballot.
The candidate who receives the fewest first choice rankings is eliminated. All ballots are then retabulated, with each ballot counting as one vote for each voter's highest ranked candidate who has not been eliminated. Specifically, voters who chose the now-eliminated candidate will now have their ballots added to the totals of their second ranked candidate -- just as if they were voting in a traditional two-round runoff election -- but all other voters get to continue supporting their top candidate who remains in the race. The weakest candidates are successively eliminated and their voters' ballots are added to the totals of their next choices until two candidates remains. At this point, the candidate with a majority of votes is declared the winner. (Some jurisdictions choose to end the count as soon as one candidate has a majoirty of votes, as this cannot cannot be defeated.)
Instant runoff voting allows for better voter choice and wider voter participation by accommodating multiple candidates in single seat races and alleviating the "spoiler effect," which can result in undemocratic outcomes. IRV allows all voters to vote for their favorite candidate, while avoiding the fear of helping elect their least favorite candidate. It ensures that winners enjoy majority support when matched against their top opponents.
Although used in most American elections, plurality voting does not meet these basic requirements for a fair election system. Compared to traditional runoff elections, IRV saves tax dollars, reduces money in politics and elects winners when turnout is highest.