The Still Secret Ballot: Limited Privacy Cost of Transparent Election Results

• In Event: Threats and Reforms to U.S. Elections

Abstract

After an election, should election officials release an electronic record of each ballot? The release of such cast vote records could bolster the legitimacy of the certified result. But it may also facilitate an unravelling of the secret ballot. Election administration across democracies, and jurisdictions within the U.S., vary in how they approach to this privacy-transparency tradeoff. However, policymakers are ruling on this tradeoff with little empirical guidance as the integrity of U.S. elections is questioned. We provide the first empirical study of the extent of vote revelation under several possible election reporting regimes, including individual ballot records. We marshal insights from the formal privacy literature and take ballots from Maricopa County, Ariz., as a case study. We find that cast vote records could reveal less than 0.2% of any voters' choices in the 2020 general election. We find that no single party is disproportionally harmed by revelation, but voters casting provisional ballots are over 250 times more likely to have their vote revealed. Our results are consistent with a statistical model in which geographic sorting and the size of reporting units determine the expected degree of revelation.

Authors

• Shiro Kuriwaki, Yale University

• Michael Morse

• Jeffrey Lewis, UCLA