Compulsory voting
Compulsory voting is increasingly resented by citizens in some countries such as Brazil, the largest country where compulsory voting is enforced: at the last presidential election in 2014, some 30 million voters, about 21% of registered voters, did not vote, despite the fact that Brazil has some of the most severe penalties enforced against non voters.
Instant-runoff voting
Because the ballot marking is more complex, there can be an increase in spoiled ballots. In Australia, voters are required to write a number beside every candidate, and the rate of spoiled ballots can be five times higher than plurality voting elections. Since Australia has compulsory voting, however, it is difficult to tell how many ballots are deliberately spoiled. Where complete rankings are not required, a ballot may become exhausted if none of the ranked choices on that ballot advance to the next round.