New York Times

CAMBRIDGE, Mass. — Last Friday afternoon, in an enormous tent in Radcliffe Yard at Harvard, Justice Ruth Bader Ginsburg gave a public interview before an adoring audience of about 1,300 people. She discussed her triumphs as a litigator, dodged oblique questions about gay rights and described an opera that premieres next month called “Scalia/Ginsburg.”

This was by one count Justice Ginsburg’s 23rd public appearance in the Supreme Court’s current term, which began in October and will conclude this month with blockbuster decisions on health care andsame-sex marriage.

But Justice Ginsburg is a bit of a laggard in terms of extrajudicial appearances. According to Scotus Map, an ambitious new website that tries to keep up with the justices’ outside activities, Justices Sonia Sotomayor and Antonin Scalia have each made more public appearances this term.

“Justice Ginsburg comes in at a respectable third, though most of her events tend to be bunched in the D.C. or New York areas,” said Victoria Kwan, one of the creators of Scotus Map. “The distribution of events for Sotomayor and Scalia — and Scalia especially — is more spread out across the country.”

Tracking the public appearances of the justices is surprisingly hard. They are public officials and public figures, and they seem to like the acclaim and influence that come from appearances before friendly audiences. But many of them appear wary of more general public scrutiny.

“The court does not release the justices’ speaking schedules ahead of time and only posts transcripts of the appearances on the court website if the justice volunteers them,” said Ms. Kwan, who founded Scotus Map along with Jay Pinho. “We are under no illusion that we have compiled all of the events out there.”

Scotus Map gathers 90 percent of its information from web and social media searches, Ms. Kwan said, with the rest coming from “tips from friends and Twitter followers.”

“I would guess that in the past 10 months Scotus Map has existed,” she said, “it’s probably collected about 70 to 80 percent of the justices’ appearances.”

“Sometimes we won’t find out that an event happened until weeks or months afterward, via an online newsletter or someone’s Throwback Thursday selfie with Justice Alito,” Ms. Kwan said. (Justice Samuel A. Alito Jr. has made at least 13 public appearances in the current term.)

The recent flurry of public appearances is part of a trend that has been decades in the making. As the court’s workload has dropped, the justices have found time for more outside appearances.

“The modern period, and the last decade in particular, has seen an explosion of Supreme Court justices being publicly reported on and being seen to some extent as celebrities,” said Richard L. Hasen, a law professor and political scientist at the University of California, Irvine.

Professor Hasen is the author of a new study that tries to quantify the phenomenon, using news reports on justices’ appearances from 1960 on. He found 196 appearances in the 1960s and just 95 in the 1970s. In the last decade, from 2005 to 2014, the number of appearances rose to 880.

Professor Hasen’s study includes a Celebrity Index, calculated by dividing a justice’s appearances by his or her years on the court. Justice Sotomayor comes in first. She is followed by Justice Stephen G. Breyer and Justice Arthur J. Goldberg, who packed a lot of appearances into his three years on the court in the 1960s.

The rest of the top 10 is made up of the current members of the court. Justice Clarence Thomas, taciturn on the bench, is loquacious off it, coming in fifth. Bringing up the rear on the current court are Chief Justice John G. Roberts Jr. and Justice Elena Kagan.

Professor Hasen’s data has limitations. Not all appearances give rise to news reports, and not all news reports, especially ones before the digital era, are easy to find.

The court’s own website is of almost no help. The page devoted to the justices’ speeches features only 51 from the last 10 years, and 29 of them are from Justice John Paul Stevens after he retired in 2010. (He contributed just one speech as a sitting justice.)

Justice Ginsburg posted 16 of her speeches in those years, and Justice Breyer five. No other member of the court has posted a single speech in Chief Justice Roberts’s 10-year tenure.

Justice Ginsburg will take part in another public interview in two weeks, atthe annual convention of the American Constitution Society, a liberal legal group. Other members of the court’s liberal wing, including Justices Stevens and Sotomayor, have also spoken before the group.

On the other hand, Justices Scalia, Alito and Thomas, members of the court’s conservative wing, have addressed the Federalist Society, a conservative group.

There seems to be vanishingly little crossover.

“I could find no record of a sitting liberal Supreme Court justice addressing the annual Federalist Society meeting or a sitting conservative Supreme Court justice addressing the annual American Constitution Society meeting,” Professor Hasen wrote.

That pattern, he said, sends an unfortunate message: “It gives the impression to the public that the justices are on one side or the other,” he said in an interview.

On Friday under the tent, an ebullient Justice Ginsburg received the Radcliffe Medal and several standing ovations.

Her appearance and others like it are valuable, said Mr. Pinho, one of Scotus Map’s founders.

“Anything that illuminates the work and even just the thought processes of the justices is extremely interesting to those of us that don’t follow the ins and outs of Supreme Court jurisprudence on a daily basis,” he said.

Ms. Kwan said the site had asked the court to provide it with the justices’ speaking schedules.

“We have not heard back,” she said.