The current U.S. Supreme Court, from left, is made up of Justices Sonia Sotomayor (top left), Stephen G. Breyer, Samuel A. Alito Jr., Elena Kagan, Clarence Thomas (bottom left), Antonin Scalia, John G. Roberts Jr., Anthony M. Kennedy and Ruth Bader Ginsburg. (Pablo Martinez Monsivais/AP)

Every version of the Supreme Court is different from the one that came before, and the current edition, it has been widely noted, is unusual in many ways.

It is the first with three women and the only one with no Protestant. Four of the five boroughs of New York City are represented, while no state between the East Coast and California can claim a single native son or daughter.

And when law professor Benjamin H. Barton loaded into a computer a pile of information about the life experiences of every justice from John Jay to Elena Kagan, the most surprising thing he found about the current court “was the breadth of how unusual they are.”

The group of nine headed by Chief Justice John G. Roberts Jr. is an “outlier” in several ways from the 105 versions of the court that have come before, wrote Barton, who teaches law at the University of Tennessee.

“Roberts Court justices have spent more pre-appointment time in legal academia, appellate judging, and living in Washington, D.C. than any previous Supreme Court,” Barton wrote. “They also spent the most time in elite undergraduate and law school settings.”

Time spent in those pursuits, according to Barton, means a deficiency of other experiences.

“The Roberts Court justices spent less time in the private practice of law, in trial judging, and as elected politicians than any previous court.”

In fact, the Roberts court is the first to not have a justice who previously served in elected office. As Barton notes, Supreme Court justices have included a president, several governors and mayors, 14 senators and 17 representatives. When Justice Sandra Day O’Connor, a former Arizona legislator, retired in 2006, it broke a string of politicians on the court that dated from its creation in 1789.

Other ways in which the current court stands out:

● While the average justice spent 17 years in private legal practice, a Roberts Court justice averages only six years of private practice. “The only two justices in the history of the court with no private practice experience,” Barton wrote, are currently serving: Justices Stephen G. Breyer and Samuel A. Alito Jr. Both spent extensive time in government.

● Members of the current court, however, spent a collective 95 years in legal academia, more than any previous court. Justices Antonin Scalia, Anthony M. Kennedy, Ruth Bader Ginsburg and Breyer all had extensive careers in teaching, and Kagan was the first female dean of the Harvard Law School.

● Even though every justice except Kagan came to the high court from the bench, almost all of that experience was in the rarified stratus of the appeals courts. Only Justice Sonia Sotomayor served as a trial court judge, and none served in state courts.

To Barton, all of that adds up to a not particularly flattering portrait of the current court:

“These cloistered and neutral experiences offer limited opportunities for the development of the most critical judicial virtue: practical wisdom.”

He acknowledges that there is another way to look at it: “Supporters can argue that this court is the most qualified of any court in history — they have spent more time considering and studying constitutional theory and the court itself than any other group.”

And he acknowledges that his approach of quantifying the justices’ year-to-year experiences cannot accommodate other characteristics.

It “must ignore other important questions of diversity and experience, like religion, ethnicity and family background, as those experiences tend to be life long and not reducible to a firm set of years,” Barton wrote.

He said that will be the next study.

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