The 'Odd Party Out' Theory of Certiorari

54 Pages Posted: 22 Jul 2020 Last revised: 16 Jun 2021

See all articles by Adam Bonica

Adam Bonica

Stanford University

Adam Chilton

University of Chicago - Law School

Maya Sen

Harvard University - Harvard Kennedy School (HKS)

Date Written: February 12, 2020


How justices advance their ideological preferences is among the most well-studied aspects of the Supreme Court. In contrast, we explore how justices may discourage ideologically motivated behavior: granting cert petitions when there is a likelihood that ideological bias influenced the lower court. We theorize that cert is more likely when there is ideological distance between the parties and the lower court panel is ideologically distant to the losing side. In these cases, the party petitioning for cert becomes the “Odd Party Out,” which conveys information about the possibility of lower court bias. We test the theory using a new dataset of nearly 18,000 cert petitions that incorporates advocate and judge ideology. We find strong support: Cert is more likely when the petitioner—regardless of their ideology—is the ideological Odd Party Out. This provides evidence that justices may disregard their own ideological concerns and intervene against ideologically driven behavior in lower courts.

Keywords: Supreme Court, Certiorari, Judicial Behavior, Judicial Ideology, Political Ideology

Suggested Citation

Bonica, Adam and Chilton, Adam and Sen, Maya, The 'Odd Party Out' Theory of Certiorari (February 12, 2020). HKS Working Paper No. RWP20-020, Available at SSRN: or

Adam Bonica

Stanford University ( email )

Stanford, CA 94305
United States

Adam Chilton (Contact Author)

University of Chicago - Law School ( email )

1111 E. 60th St.
Chicago, IL 60637
United States


Maya Sen

Harvard University - Harvard Kennedy School (HKS) ( email )

79 John F. Kennedy Street
Cambridge, MA 02138
United States


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