WASHINGTON - During a long and sometimes contentious day of questioning, Supreme Court nominee John G. Roberts Jr. called the landmark 1973 abortion rights case "settled as a precedent of the court."

But he stopped short yesterday of pledging to members of the Senate Judiciary Committee that the decision in Roe v. Wade should never be overturned.

From the opening moments of the second day of Roberts' confirmation hearing, Roe and the right to privacy it was built on were a topic of conversation between the 50-year-old nominee for chief justice and the committee members.

Roberts said the right to privacy could be found in several places in the Constitution, including the due process clause of the 14th Amendment. But he resisted attempts from several senators to get him to express a personal opinion about prior abortion decisions, saying he could not discuss in detail anything that's likely to come before the court.

"That's one of the areas where I think prior nominees have drawn the line when it comes to, 'Do you agree with this case or do you agree with that case?'" said Roberts, a federal appellate judge for the past two years. "And that's something that I'm going to have to draw the line in the sand."

Roberts drew a similar line on other issues, from the separation of church and state to whether Congress has the power to pull the nation out of a war.

If Roberts is confirmed, he will hear an abortion case during the court's fall term, which begins Oct. 3. The New Hampshire case involves a state law requiring females under the age of 18 to have parental permission to obtain an abortion.

Over the course of more than nine hours of questioning, Roberts addressed a broad range of topics, from his views on the separation of powers to whether the court should look to foreign laws for precedents. He sparred with a few Democrats - Sen. Joseph R. Biden Jr. of Delaware accused him of "filibustering" during the most heated exchange - but he continued to display the quick thinking and calm manner that he had shown Monday.

While the tone of the hearing remained relatively cordial, senators repeatedly came back to the subject of abortion rights.

Promptly at 9:30 a.m., Judiciary Committee Chairman Arlen Specter, a Pennsylvania Republican, went right to the question that has come to dominate Supreme Court confirmation hearings since Roe v. Wade was decided. Specter asked Roberts to explain his comment that Roe was "settled law" and to provide his thoughts on the principle of stare decisis, Latin for "let the decision stand."

Roberts, who spoke at Monday's session of the need for stability in the legal system, said he respects the power of precedent, adding that justices must think of how entrenched a particular ruling has become in society before considering whether to overturn it.

"I do think that it is a jolt to the legal system when you overrule a precedent. Precedent plays an important role in promoting stability and evenhandedness," Roberts said. "It is not enough that you may think the prior decision was wrongly decided. That really doesn't answer the question; it just poses the question."

Other factors are involved, he said, such as whether the system created by a ruling is workable, and whether other subsequent decisions have chipped away at the initial case.

And there are times, he said, when overruling an established case is "a price that has to be paid."

The most obvious example, Roberts said, is the 1954 decision in Brown v. Board of Education, which declared school segregation unconstitutional - a direct reversal of the decision in an 1892 case that permitted separate facilities, as long as the conditions were equal.

Roberts, a devout Catholic, also said that religion would not affect his legal reasoning on issues such as abortion rights. He did say that he agreed with the court's 1965 decision in Griswold v. Connecticut, which established that married couples had the right to obtain contraceptives.

He said there is "nothing in my personal views based on faith or other sources that would prevent me from applying the precedents of the court faithfully under principles of stare decisis."

The hearing resumes with more questions today. The Judiciary Committee is expected to vote on Robert's nomination next week, and barring a major revelation, the full Senate is likely to confirm him as the youngest chief justice in more than two centuries before the end of the month.

After their questioning ended yesterday, several Democratic senators said they wished Roberts had been more forthcoming.