Another common criticism of RCV is how it handles ballots that do not include preferences for all candidates.

For example, suppose a group is planning a vacation and asks everyone to list their preferred vacation destinations. You might list your top choices, but not bother ranking every place you would be willing to visit. Even with a small number of options, you might still choose to list only your first choice.

You may have preferences beyond your top choices, or you may be indifferent. For example, you might list Playa del Carmen, but not include nearby Cancun or a more distant option like Hawaii. The final decision could come down to Cancun versus Hawaii. Some might assume that because you listed Playa del Carmen, your preference should lean toward Cancun, since both are in the Riviera Maya. Others might assume that because you did not list either option, you are indifferent. From the list alone, there is no way to know whether you prefer Cancun or Hawaii.

Ranked ballots work the same way. If a ballot does not include a ranking for the remaining candidates, there is no information about what the voter would prefer next, if anything. When this occurs during counting, the ballot does not continue to later rounds. An exhausted ballot is a ballot that no longer has a ranked candidate remaining in the race.

How these situations are handled depends on the ballot design and counting rules. As candidates are eliminated, only ballots that include a ranking for the remaining candidates continue to be counted. Ballots without additional rankings remain part of the total ballots cast, but do not affect later rounds of counting.

This effect can be seen in the following example.

Returning to the wilderness example, suppose there is one Forester candidate (the Bear) and two Feline candidates (the Tiger and the Cheetah).

The Foresters make it clear they prefer the Bear, and have no preference between the Tiger and the Cheetah. The Jungle Group makes it clear they prefer the Tiger, and list the Cheetah second because they do not like the Bear. The Plains Group only votes for the Cheetah and provides no information about whether they have any preference between the Bear and the Tiger.

Instant Runoff Voting

Now, suppose this election is run in an Instant Runoff Voting (IRV) election. We start by comparing the first-place votes:

The Cheetah with the fewest first place votes is eliminated. The 25 ballots with the Cheetah ranked first do not include a second ranking, so they do not continue. The process continues between the Bear and the Tiger:

And the Bear wins with a majority of the final votes, but not with a majority of the total votes. Members of the Feline community may be outraged by these results, because Feline candidates combined for more total votes than the Bear. They may call Ranked Choice Voting a partisan plot by Foresters to rig elections, and argue that the Felines as a whole were disenfranchised by having their ballots thrown in the garbage or set on fire.

It may be that the Plains Group did not fully understand the ballot. Or it may be that they simply did not have an opinion between the Tiger and the Bear. It is impossible to know whether they would have shown up if the race had been only between the Tiger and the Bear, or if there had been a runoff election.

Critics of IRV would describe the Tiger as a spoiler candidate. If the Tiger had not run, the Jungle group indicated they would have supported the Cheetah over the Bear to reach their best achievable outcome. However, because the Plains voters indicated no preference between the Tiger and the Bear, the Felines had an incentive not to run the Tiger and risk losing Plains support if the Cheetah was eliminated first.

Head-to-Head Record

We will also look at how this example would have played out using Head-to-Head Record. The results would have been:

All three candidates would have been tied with the same record. In that case, a cycle-resolution method or tiebreaker would likely be used. Note that in this case, vote differential, Ranked Pairs, and Schulze would all favor the Cheetah, and the Tiger would not have acted as a spoiler candidate. Without additional rankings from the Plains group, there is no way to determine how those voters would compare the remaining candidates.

Exhausted ballots are not the result of a mistake in counting, but a consequence of incomplete information. When voters do not rank additional candidates, there is no way to determine their preferences in later rounds. This can produce outcomes that feel counterintuitive, especially when groups appear to have more combined support. At the same time, assigning preferences that were never expressed would introduce assumptions that may not reflect the voter’s intent. As a result, exhausted ballots highlight a core tradeoff in ranked choice voting between using only the information provided and attempting to infer preferences that are not on the ballot.