Although participation of amicus curiae at the certiorari stage was once rare, lawyers now regularly urge the Court to hear specific cases on behalf of their non-party clients, and thus it is worth asking whether amicus participation at the cert. stage is effective.
Political scientists Gregory Caldeira and John Wright have attempted to answer that question. In a recent paper, entitled Organized Interests Before the Supreme Court: Setting the Agenda, they have followed up on their influential 1988 article examining the role of amicus briefs in Supreme Court case selection. In the 1988 article, Caldeira and Wright concluded that amicus briefs filed at the cert. stage have a statistically significant effect on the Supreme Court's case selection. That paper was based entirely on data gathered during OT1982, however"”a year the authors acknowledge may have been anomalous. And some critics argued that Caldeira and Wright had not sufficiently controlled for the possibility that amicus are more likely to participate in cert.-worthy cases. Thus, Caldeira and Wright delved back into the data to update their statistics and respond to their critics.
In their new paper, Caldeira and Wright added data from OT1968 and OT1990 and controlled for a host of additional variables relevant to the Court's decision to take cases. (The 1988 paper had controlled for factors such as participation by the United States and conflict among the lower courts; the recent paper added factors such as the presence of dissenting opinions in the lower courts and whether the petition was filed by a state attorney general, among many others.)
The new data confirm their original conclusion that amicus briefs are influential, ranking alongside participation by the United States and conflict among the circuits as one of the three best predictors of whether the Court will hear the case. Interestingly, Caldeira and Wright also found that more is more: that is, that the probability of a cert. grant increases with each additional amicus brief filed. (In light of this data, it is interesting to look back at SCOTUSblog’s 2007 study of the identity of amici at the cert.-stage, which found that pro-business and pro-regulatory groups were the most active participants at the cert. stage.)
Caldeira and Wright's paper does not tell us why amicus briefs are influential, however. Perhaps the mere willingness of parties to participate at the cert. stage signals to the Court that the case is an important one, or perhaps the substantive arguments made in those briefs persuade the Court to take the case. In his book, Friends of the Supreme Court: Interest Groups and Judicial Decision Making, Professor Paul Collins has concluded that amicus briefs are influential for both reasons. Professors Joseph Kearney and Thomas Merrill reached similar conclusions in The Influence of Amicus Curiae Briefs on the Supreme Court, 148 U. Pa. L. Rev. 743 (2000). All of these are worthwhile reading for those who regularly participate as amicus curiae in the Supreme Court.