One of the more difficult questions facing Supreme Court scholars is trying to decipher the impact of the litigants. Given the secrecy with which the Supreme Court conducts the majority of its business, any effort towards understanding the decision making process is inevitably met with frustration.  The most recent insight we have into any of the Court’s deliberations is from way back in 1993.

The chicken and the egg problem described here involves looking at the litigants’ briefs and the Court’s opinions and based on this information trying to infer what role the briefs had in the Court’s decisions.  This is difficult for multiple reasons.  The justices and clerks have multiple sources of information in front of them aside from the litigants’ briefs in the form of lower court transcripts and briefs from amici.  The justices and clerks might come up with certain sources of information independent from the briefs or the justices might use the briefs to tap into certain information. Without a direct source to answer this question we may never know the answers definitively.

In a paper I wrote previously, I found that even compared to these other case elements, the Court shared more language with the parties’ merits briefs than with either of the other two sources.  To peel away layers of the onion a bit more, this post takes a basic look at the relative amount of law shared between Court opinions and the parties’ merits briefs. The question itself is somewhat basic: which parties’ briefs does the Court share more citations with and does this matter?

To come up with a measurement strategy, I simply took the cases cited in the main text (excluding footnotes) of each of the Court’s majority opinions for the October through March sittings of the 2016 Supreme Court term and compared these to the cases cited in all main parties’ briefs.

First a look at the number of cases cited within each majority opinion:

Presumably there is a greater chance that the Court will share a higher percentage of citations with briefs when it cites a smaller number of cases rather than a large number of cases. This is indeed the case as the following figure conveys (the percentages are based on the number of cases cited in an opinion that are also cited in a give brief).

[Note: P and R denote petitioner and respondent]

The Court shared 80% or more of the cases cited with 15 out of the 103 briefs analyzed.  Of these 15, the Court shared all citations with six briefs or about 6% of those examined.  These briefs were authored by (the author is the counsel of record noted on the brief) – Neal Katyal in Endrew F, Adam Unikowsky in Honeycutt, ex-SG Ian Gershengorn in Manrique, Clifford Sloan’s and Scott Keller’s briefs in Moore v. Texas, and John Williams’ brief in Turner.  Out of those cases, the greatest number of distinct cases cited in the majority opinion was in Justice Breyer’s opinion in Turner with five.   Also interestingly, the Court shared this high percentage of language with multiple merits briefs in five of the ten cases mentioned above. This makes assessing the more impactful brief even more of a difficult task.

It also may not be surprising that the Court often shares a large percentage of cited cases with the SG’s briefs since the SG is often touted as the most trusted source of information for the Court.  Still, the Court did not share a high percentage of cited cases with all of the SG’s briefs examined.

In two cases – Sessions v. Morales-Santana and NLRB v. SW General – the Court shared a low percentage of cites with the SG’s briefs at 17% and 13% respectively.  As it turns out, the SG represented the prevailing party in Morales-Santana although not in SW General.  In fact, there seems to be little relationship between the brief the Court shares more citations with and the prevailing party.  The Court shared a greater percentage of cases cited with the prevailing parties brief in only 19 of the 49 cases examined or in about 39%.

There are many issues worth further exploration along similar lines. Other intriguing similar topics include looking at which briefs the Court shares more non-Supreme Court citations with, which briefs the Court shares more non-case citations with, which briefs the Court references more (a question I somewhat previously examined), etc. Without greater transparency from the Court, finding more answers to these chicken and egg questions will be a tricky task at best. Hopefully some of this work will help fill in the large gaps.

On Twitter: @AdamSFeldman