This paper aims to explain why the Korean electoral reform to a partial compensatory electoral system failed to produce a fairer representation in the 2020 National Assembly election. It focuses on the collective split-voting strategy with which major parties can manipulate an electoral loophole inherent in an MMP system to rationally maximize their number of seats in the Assembly. During the campaign the two major political parties, the Democratic Party and United Future Party, launched their clone parties and mobilized supporters to collectively cast a split-ticket voting. And this made the two votes independently counted and led to over-representation of the major parties at least in the PR tier. As a result, the collective split-voting strategy converted the seat allocation process under a partial MMP system into an MMM-like system. With hypothetical simulations and the scrutiny of actual electoral outcomes, this paper explains how the collective split-voting strategy worked in the election and shows it may undermine the legitimacy of a newly adopted electoral system in Korea.
II. Theories of Strategic Split-Ticket Voting under Mixed Electoral Systems
III. Changing Electoral System and Clone Party Politics in Korea
IV. Hypothetical Simulations and The 2020 National Assembly Election
V. Conclusion and Speculation about Future Reform