In the early 1980s, the Supreme Court decided more than 150 cases a year. These days, it decides about half that many.
A couple of weeks ago, the Supreme Court advocacy clinic at Yale Law School held a conference to explore the mystery of the court’s shrinking docket. Law professors presented data, theories and speculation. Expensive lawyers told rueful stories about can’t-miss cases that somehow did not make the cut.
Some participants blamed the newer justices, others their clerks. Some blamed Congress, saying it is not cranking out enough confusing legislation. And some blamed the Justice Department, which is filing fewer appeals.
But there emerged nothing like a definitive answer to why the court now selects perhaps 80 cases from more than 8,000 requests for review it receives every year.
The most striking possible explanation came from David R. Stras, a researcher at the University of Minnesota Law School. A crop of five new justices who joined the court starting in 1986, he found, voted to hear cases far less often than the justices they replaced.
“You saw the docket fall off a cliff” as these justices took their seats, Mr. Stras said in an interview.
It takes the votes of four justices to hear an appeal — or, in the language of the court, to grant a petition for a writ of certiorari. Mr. Stras examined all of the more than 2,500 appeals from 1986 to 1993 that attracted at least one such vote, drawing on the papers of Justice Harry A. Blackmun, which contain the most recent publicly available data.
The starkest difference was between Justice Byron R. White, who voted to hear an average of 216 cases per term from 1986 to 1992, and his replacement, Justice Ruth Bader Ginsburg, who voted to hear 63 cases in 1993.
The phenomenon seemed to cut across ideological lines. Justice Clarence Thomas voted to hear 72 cases per term, down from Justice Thurgood Marshall’s 125. Justice David H. Souter voted to hear 83 cases per term, down from Justice William J. Brennan Jr.’s 129.
Factors other than a change in personnel were plainly at work in those years as well, as the four justices who stayed on also voted to hear somewhat fewer cases with passing years. But that drop was not as steep as the one for the five new justices.
The effect of adding those new justices, Mr. Stras found, meant that by 1993 the Supreme Court was “essentially operating with the functional equivalent of only seven of the members of the pre-1990 court.”
Four more justices have joined the court since 1993, and the docket has remained small, reaching a modern low of 70 decisions in the term that started in October 2007. (There are various ways to calculate what counts as a decision; Professor Stras used The Harvard Law Review’s numbers, which include some unsigned opinions.)
Another factor contributing to the shrinking docket may be the “cert. pool,” the arrangement in which many of the justices share their law clerks to assess the thousands of petitions from which the court culls the cases it will hear. A single clerk writes a “pool memo” evaluating the case, and the memo is distributed to the participating justices.
The number of justices in the pool grew to eight from six from 1989 to 1991, and that may have driven down the number of petitions granted, according to Kenneth W. Starr, a former appeals court judge, solicitor general and independent counsel in the Whitewater investigation. (Seven justices are in the pool now. The exceptions are Justices John Paul Stevens and Samuel A. Alito Jr.)
“The prevailing spirit among the 25-year-old legal savants, whose life experience is necessarily limited in scope, is to seek out and destroy undeserving petitions,” Mr. Starr wrote in The Minnesota Law Review in 2006.
The solicitor general’s office, which represents the federal government in the Supreme Court and enjoys a very high success rate in persuading the court to hear its cases, has also been playing a role.
According to a paper prepared by Adam Chandler and Jennifer Harris of the Yale clinic, the average number of petitions filed by the solicitor general in the last four terms was about 16. In the previous four terms, the average was 29.
Speaking at a judicial conference in July, Solicitor General Elena Kagan said her office’s high rate of success may be the product of excessive caution.
“I think they’re up to about 70 percent of the time they’ll take our advice,” Ms. Kagan said of the justices. She then recalled advice she used to give colleagues in her last job, as dean of Harvard Law School: “If you don’t fail sometimes, that means you’re not trying to do enough things.”
In 1987, when Justice Ginsburg was still a federal appeals court judge, she asked the most important question in this controversy, in an article she wrote with Peter Huber in The Harvard Law Review: “How much Supreme Court judging does the country really need, and is it currently getting too little?” The article’s answer was that the court was deciding cases “often enough.”
But Judge Ginsburg wrote just before the number of cases on the docket started to plummet. These days, many scholars and practitioners say the court is not operating at peak capacity and is not an active enough participant in a dialogue with the lower courts.
At the Yale conference, though, there were dissenters from that sentiment.
“The dangers of deciding are often vastly greater than the dangers of letting the political branches and the lower courts wrestle a question through,” Judge J. Harvie Wilkinson III, of the United States Court of Appeals for the Fourth Circuit, said in a paper he presented the conference.
“If we cannot trust the Supreme Court’s judgment in deciding what to decide,” Judge Wilkinson added, “how can we trust its judgment in deciding what it has decided to decide?”