Voter Equalization and Turnout Bias After Electoral Reform: Evidence from Chile’s Voluntary Voting Law Daniel Brieba Kenneth Bunker ABSTRACT It has normally been argued that because compulsory voting systems present higher turnout rates relative to voluntary voting systems, they do not generate as many biases between different groups of voters. Tis article qualifies that view. It argues that in cases in which compulsory voting does not ensure near-universal participa- tion, there is no certainty that switching to voluntary voting will increase inequal- ities. Tis issue is examined by looking at Chile, a democracy that moved from compulsory voting to voluntary voting in 2012. Te research finds that while the reform generated class bias in urban districts, it also substantially reduced age bias and, in national elections, equalized participation between small and large districts. Te conclusion is that abandoning compulsory voting does not necessarily increase turnout biases, since much depends on the structure of preexisting biases and how these are conditioned by particular electoral institutions. Keywords: compulsory voting, Chile, class bias, electoral reform, turnout bias E lections are the main mechanism through which citizens make their preferences heard in a democracy. However, not everyone who can vote chooses to do so. Tis is a problem, inasmuch as a “core assumption of liberal democratic theory is that . . . those who participate in the political process will have better representation of their interests than those who do not participate” (Avery 2015, 956). According to Lijphart (1997), such inequalities in participation constitute a democratic “dilemma.” If large groups exclude themselves persistently enough, they may skew public policy against them. Tus, what matters is not so much the level of overall participation but rather the bias in turnout between different population groups. Along these lines, class bias is a central concern: if the rich vote more, they may get more than their due in the policy process. Te underlying mechanism for this intuition is captured in Meltzer and Richard’s 1981 model, in which the level of redistribution is determined by the median voter. If the poor vote less than the rich, © 2019 University of Miami DOI: 10.1017/lap.2019.23 Daniel Brieba is an assistant professor at the Escuela de Gobierno, Universidad Adolfo Ibáñez. daniel.brieba@uai.cl. ORCID 0000-0002-0864-2193. Kenneth Bunker is a visiting professor in the Dipartimento di Scienze Sociali e Politiche, Università degli Studi di Milano. kabunker@gmail.com. ORCID 0000-0002-4579-6132.