Litigation Department Chair John S. Summers and co-authors Michael J. Newman and Michael Cliff, PhD have published the article entitled “An Econometric Investigation of the Determinants of US Supreme Court Decisions,” which appears in Volume 83.4 of the Tennessee Law Review.

In the article, the authors examine the decisions of the first eight terms of the Roberts US Supreme Court (October 2005 through 2012) to evaluate the variables that may explain the more than 4,150 votes by the ten Justices who sat on the Court during this period.  The results include:

  1. Advocacy experience before the Supreme Court matters

Clients and advocates with cases before the Supreme Court will be particularly interested in our finding that relatively experienced Supreme Court oral advocates are more likely to succeed by the Court against less experienced adversaries.  Analysis found that the 20% most active advocates in a year had a significantly greater likelihood of success when they opposed an advocate not among the 20% most active.  Also, those advocates with a better batting average before the Supreme Court were more likely to prevail against advocates with a lesser record.

  1. Amicus support, particularly from the Solicitor General’s Office, correlates with success before the Court

Of particular interest as the Trump Administration nominates an Attorney General and Solicitor General, the study shows that a party before the Supreme Court enjoys a very substantial (10.6 percentage points) greater likelihood of success if the SG’s Office is on its side and submits a supporting brief.  This result suggests that who heads the SG’s office will be very influential in the decisions of the Supreme Court.  However, one caveat:  Because the statistical analysis can show only that SG support correlates with a party’s success, not that the support caused success, this finding results from the SG’s Office being strategically effective in identifying the positions that would otherwise prevail before the Supreme Court, and not from the SG’s Office being extraordinarily persuasive or influential.

  1. Ideology matters in at least two ways

As the country looks ahead to the debate over the confirmation of a replacement for Justice Antonin Scalia, the study confirmed what is well accepted – ideology matters.  The study shows this in two ways.

First, the authors examined the match between the ideological direction of the court of appeals decision under review (i.e., is it liberal or conservative leaning) with the party affiliation of the President who appointed the Justice voting in the case.  Our analysis shows that a Republican (Democrat) appointed Justice is much less (15.2 percentage points) likely to vote to reverse a conservative (liberal) leaning decision.

Second, they looked at whether a Justice appointed by a President from one political party was less likely to reverse the decision written by a court of appeals judge who was appointed by a President from the same party.  Our analysis shows that when the party of the President who appointed the Justice and judge are the same, Justices vote to reverse the lower court 5 percentage points less than show the parties differ.  Among other things, this suggests that opinions written by the fifty-five court of appeals judges appointed by President Obama will fare less well in front of the as-yet-Trump-appointed Justice than they would have had Chief Judge Merrick Garland been confirmed.

  1. Who wrote the Court of Appeals decision under review makes a difference

The study also looked at whether various characteristics of the court of appeals judge who wrote the decision under review correlated with Justices’ votes to affirm or reverse the decision.  Counterintuitively, Justices were more likely to reverse the decisions written by longer tenured members of the court of appeals than those written by newer judges to the court of appeals.  (Specifically, a judge on the court of appeals for 9 years was nearly 3.8 percentage points more likely to be reversed than a recently appointed judge.)  A possible rationale for this is that court of appeals judges are more cautious earlier in their career, perhaps “auditioning” for elevation to the Supreme Court.

Other characteristics that might serve as a proxy for the “competence” of the court of appeals judge – whether the judge was a former federal law clerk or his ABA quality rating at the time of confirmation – were found not to be statistically significant indication of reversal.

Read the article