The Condorcet Case for Supermajority Rules

56 Pages Posted: 14 Jan 2008


The Condorcet Jury Theorem has been deployed to argue that majority rule is the best voting rule for popular decisionmaking, including for legislatures. Yet the United States Constitution employs supermajority rules of various kinds as the primary decisionmaking rule. In this article, we show that modifications in the Condocet paradigm that make the model more realistic have the effect of making supermajority rules more desirable than majority rule in a variety of circumstances. First, we suggest that due to the existence of voting blocs, the number of independent decisionmakers in a legislature is less than the nominal number of legislators. Reducing the number of decisionmakers decreases the advantages of majority rule compared to supermajority rule. Given the reduced number of decisionmakers, we then explore situations when supermajority rules are superior. Supermajority rule may be more desirable than majority rule if the legislature schedules more votes on bad than good legislation. Supermajority rule may also be superior to majority rule when legislators are subject to biases. Further, supermajority rules may also have feedback effects, which may raise the skill levels of legislators, again improving the effects of supermajority rule over majority rule. Such feedback effects may help supermajority rules correct for central problems in democracy, like special interests and partisanship.

Finally, we explain that on plausible factual assumptions the Constitution's supermajority rules generally correspond to situations in which supermajority rules are desirable under a Condorcet paradigm, including the supermajority rules for impeachment, the implicit supermajority rule created by the tricameral structure for passing legislation, and the stringent supermajority rule for entrenching constitutional provisions.

We also argue that there is an insurance rationale for using a supermajority rule for entrenching constitutional provisions. Because there is often uncertainty as to how majority rule and supermajority rule will function, risk averse parties may prefer supermajority rules because their effects are less extreme than that of majority rule. Finally, we show that the Condorcet paradigm helps to justify the continuing authority of the Constitution to displace statutes.

Keywords: Supermajority Rules, Condorcet Jury Theorem, Constitution-Drafting

JEL Classification: D71

Suggested Citation

McGinnis, John and Rappaport, Michael B., The Condorcet Case for Supermajority Rules. Supreme Court Economic Review, 2008, San Diego Legal Studies Paper No. 08-001, Northwestern Public Law Research Paper No. 1081729, Available at SSRN:

John McGinnis

Northwestern University - Pritzker School of Law ( email )

375 E. Chicago Ave
Chicago, IL 60611
United States
312-503-3235 (Phone)

Michael B. Rappaport (Contact Author)

University of San Diego School of Law ( email )

5998 Alcala Park
San Diego, CA 92110-2492
United States

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