Why the Supreme Court agrees to hear cases is among the most important topics in judicial politics. However, existing theories have overlooked a key factor: the relative ideologies of the litigating parties. We develop and test a new theory that explicitly incorporates the ideology of the litigating parties in explaining which cert petitions the Court is likely to grant. Specifically, we theorize that cert petitions are more successful when (1) there is great ideological distance between the two opposing parties and (2) the lower-court appeals panel is closest ideologically to the party who won at the appellate level. In these cases, the party petitioning the Court to intervene becomes the “Odd Party Out,” which conveys information about both the importance of the case and the possibility of ideological bias against the petitioner. We test this theory using a new dataset on the identities and ideologies of advocates and judges for federal court cases that generated cert petitions from 2003 to 2015. We ?nd strong support for the theory: petitions are more likely to be granted when the petitioning party is the ideological Odd Party Out.
Bonica, Adam, Adam Chilton, and Maya Sen. "The “Odd Party Out” Theory of Certiorari." HKS Faculty Research Working Paper Series RWP20-020, January 2023.