As part of the University of Michigan’s Complex Systems Seminar Series, LSA Dean Andrew Martin spoke Thursday afternoon at West Hall about the “Martin-Quinn” scores, a measurement of the liberal or conservative ideologies of U.S. Supreme Court justices, which Martin researched and developed with Kevin Quinn from the University of California at Berkeley’s School of Law in 2002.
Martin and Quinn’s model encompasses every member of the court from October 1937 to October 2015. It was referenced in multiple academic journals, and most recently in a New York Times article on the Supreme Court.
“I think the model does a quite reasonable job of telling us something about the U.S. Supreme Court,” Martin said. “The overall project goal is that we were trying to accomplish is to develop a structural model of revealed preferences, the preferences of the nine justices who sit on the U.S. Supreme Court.”
Martin said the model focuses a lot on the “median” justice of the Supreme Court, the one who sits in the middle of the ideological spectrum and is an indicator of how the court’s ideology will impact decisions. The “median” justice is especially important for the future ideological balance of the court in the wake of conservative Justice Antonin Scalia’s passing last February, leaving the Court with only eight justices.
“The passing of Justice Scalia has put the Supreme Court at a crossroads,” Martin is quoted as saying on the LSA website. “If a Democrat appoints the next justice who is confirmed, then Justice Breyer will become the median justice and the liberals will control the court for the first time in a generation. On the other hand, if a Republican appoints the next justice who is confirmed, Justice Kennedy will once again become the median justice.”
Martin said Thursday that scholars try to make inferences about the past based on the model, but reiterated that playing hypotheticals like these are unrealistic. He said it is implausible to use the model to attempt to predict how, for example, a historical justice like Louis Brandeis would have voted on a case such as Bush v. Gore.
While the model lacks the ability to make hypothetical inferences, Martin said he believes it gives an accurate representation of the ideological climate of the court over time and allows for a deeper conversation on the future of the court, especially with a new confirmation possible soon to replace Scalia.
“We care about the ideological climate, we care about who is in the middle and we care about how that lineup and the coalition has evolved over time,” Martin said.
Emphasizing that this model is just a starting point, Martin said in the future he would like to see a similar model produced to also fit the ideological data available on the U.S. Congress.
“While we love having the model in the press and while we love having people citing it all the time, from a modeling standpoint this is just step one,” Martin said. “I hope I’ve convinced you that this is at least somewhat useful in some context.”