Chief Justice John Roberts said last fall he would like to see the U.S. Supreme Court take up more cases. So far, however, his arrival has had the opposite effect.

Justices are running well behind in filling their argument calendar for the term that begins in the fall. They have accepted 18 cases, compared with 27 by this time last year and 32 in 2004.

Many of the cases they have agreed to consider are technical rather than potentially groundbreaking.

The nine members of the court have wide discretion in deciding what cases to review. An important part of their jobs — done with substantial help of law clerks — is sifting through the nearly 9,000 appeals filed each year and picking about 80 to consider.

In recent years, under the leadership of the late Chief Justice William H. Rehnquist, justices confidently stepped into disputes over physician-assisted suicide, medical marijuana, presidential war powers and even a presidential election.

Rehnquist died last fall and was replaced by Roberts. A few months later, Samuel Alito was confirmed to replace retiring Justice Sandra Day O'Connor.

Court watchers are anxious for signs of the transition, but the cases that the new court have agreed to review have revealed little. The justices have rejected potential landmark cases including a constitutional challenge to lethal injection and an appeal on behalf of an American jailed without traditional legal rights as an enemy combatant.

"They work in their mysterious ways," said Douglas Berman, a law professor at Ohio State University. "The broader story is, is Roberts going to change the dynamic of how the court sets its agenda?"

The court has nearly 30 cases for which it has heard argument and must resolve before ending this term, so the justices may not be anxious to add new contentious issues for the fall, Berman said.

"They may think there's some value in seeing how they work together in tough cases," he said.

Justices take a three-month break at the end of June. Usually by June they have lined up cases for oral arguments in the fall. So far they have chosen just half of the cases needed to fill up their fall argument schedule.

Before becoming a judge, Roberts was a Washington lawyer who specialized in Supreme Court appeals. He said during his Senate confirmation hearing that the justices "hear about half the number of cases they did 25 years ago. There may be good reasons for that that I'll learn if I am confirmed. But just looking at it from the outside, I think ... they could contribute more to the clarity and uniformity of the law by taking more cases."

UCLA law professor Eugene Volokh said court watchers should be patient. "It's a little early to read the tea leaves," he said.