Washington ? His mother may know best, but conservatives do not share her certainty that Samuel Alito would overturn abortion rights.

Alito’s independent streak is complicating what might otherwise be an easy call as people on both sides of the abortion divide try to figure out his likely course if he were confirmed by the Senate for the Supreme Court.

The nominee’s 90-year-old mother, Rose Alito, has said of her Catholic son that “of course, he’s against abortion.” But that is her personal understanding, which is not always an accurate indicator of how a justice would vote.

“If you asked me to guess what Sam thought about abortion, it’s probably the same thing his mother said,” said Joshua I. Schwartz, a professor at George Washington Law School who worked with Alito in the solicitor general’s office during the Reagan administration.

“But obviously there is a real difference between what Sam Alito thinks is what’s right and what’s wrong and what does he think the law should be,” Schwartz said.

President Bush has nominated Alito, a judge on the Philadelphia-based 3rd U.S. Circuit Court of Appeals, to replace Justice Sandra Day O’Connor, who announced plans to retire in July.

Liberals say Alito is certain to roll back abortion rights. They contend that while Alito stuck to Supreme Court precedent as an appellate judge, he would be free as a justice to act on his personal opposition to abortion.

Abortion foes are not so sure he would vote their way. Their optimism about Alito’s nomination is tempered by their views on some of Alito’s decisions during his 15 years on the federal bench.

Conservatives cheered Alito’s 1991 vote requiring that women who seek abortions notify their spouses. But they were dismayed by his writings in three other cases:

l In 1997, in Alexander v. Whitman, Alito concurred with the appellate court’s decision that a fetus is not a person under the equal protection clause of the Constitution. A woman who delivered a stillborn baby had challenged a New Jersey law, arguing that she should be able to file a wrongful death lawsuit.

l In 2000, in Planned Parenthood of Central New Jersey v. Farmer, Alito was among the judges who invalidated a New Jersey law banning late-term abortions. He cited the high court’s decision on a Nebraska statute.

l In 1995, in Blackwell v. Knoll, Alito cited federal government policy in voting to invalidate Pennsylvania restrictions on publicly funded abortions for women who are victims of rape or incest.