WASHINGTON – The fact that both sides of the abortion debate are applauding the Supreme Court’s decision yesterday requiring a lower court to rework its nullification of a New Hampshire parental notification statute is raising questions about whether the unanimous ruling was merely a placeholder ahead of a dramatic court transition.

The case, Ayotte v. Planned Parenthood, was seen as an important first test of how Chief Justice Roberts would rule on the extent to which states are free to regulate abortion. But the court’s decision to deflect the case failed to make clear any leanings of the new chief justice. It also guaranteed that future challenges to the New Hampshire statute will be reviewed by a court that is almost certain to include Supreme Court nominee Samuel Alito.

Chief Justice Roberts assigned the opinion in the case to Justice O’Connor, who for more than two decades has maintained a centrist, if sometimes inscrutable, position on the ability of states to regulate and restrict abortion rights. She has said states may regulate abortion, but has nullified any regulation that imposes an “undue burden” to access. The undue burden standard has bedeviled lower courts for years.

Judge Alito, whose confirmation is expected late next week, drew fire from Democrats during his confirmation hearing last week because of his dissent in a 1991 abortion case in which he interpreted Justice O’Connor’s undue burden standard more narrowly than his colleagues on the federal Court of Appeals for the 3rd Circuit. Court watchers said Judge Alito could interpret the undue burden standard more freely on the Supreme Court.

“Activist groups on either side may be inclined to claim a big victory today,” the senior attorney for Americans United for Life, Clarke Forsythe, said. “But basically what this decision does is leave the status quo intact while the court is in transition.”

At issue in yesterday’s case was whether a so-called judicial bypass that allows minors to get permission for an abortion from a court in an emergency satisfies a decades-old health exception requirement for abortion restrictions. Justice O’Connor affirmed earlier court rulings that states are free to regulate abortion through parental notification statutes. She also affirmed the court’s previous rulings requiring a health exception for state abortion regulations.

But the lower court was wrong to overturn the entire law, Justice O’Connor wrote, since “only a few applications” of the parental notification statute would be unconstitutional. She said that a new decision by the lower court in which the underlying law is retained and the unconstitutional elements corrected is preferable to having the Supreme Court decide the issue itself.

“In this case, the courts below chose the most blunt remedy,” Justice O’Connor wrote, “permanently enjoining the enforcement of New Hampshire’s parental notification law and thereby invalidating it entirely … in the case that is before us, however, we agree with New Hampshire that the lower courts need not have invalidated the law wholesale.”

Opponents of abortion rights immediately embraced the decision, saying that it affirmed the rights of states to regulate abortion.

“Today’s decision reaffirms that parents have a right to know and that girls have a right to have their parents involved,” the legislative director for the National Right to Life Committee, Mary Spaulding Baulch, said. “It is a victory both for parents and for minor girls.”

Abortion rights supporters also rallied around it, citing Justice O’Connor’s reaffirmation of the health exception standard.

“This is a decision being welcomed by our friends and allies at the American Civil Liberties Union and Planned Parenthood who were the lawyers on this case,” a spokeswoman for NARAL Pro-Choice New York, Mary Alice Carr, said. “The first thing that has become clear on this is that it says we can’t jeopardize a woman’s health by not including the health exception – that the health exception has to be included in the law.”

But some court watchers said the shared excitement on both sides of the debate obscured a potentially significant victory for opponents of abortion rights, particularly with the shape of the court in flux. They said the difficulty that the Court of Appeals for the 1st Circuit had in crafting a decision that respects the health exception could provide greater evidence that existing abortion jurisprudence is unworkable – one of three criteria cited by Chief Justice Roberts during his confirmation hearing for revisiting a precedent.

A constitutional law professor at the Pepperdine University School of Law, Douglas Kmiec, said the decision represented a small but notable departure from a 2000 case, Stenberg v. Carhart, in which the Supreme Court ruled that abortion restrictions that are found to be unconstitutional in any application are invalid.

“When the court remands a case to the lower courts and says ‘Can you fashion a narrower remedy,’ it is effectively saying you should not be quick to invalidate abortion restrictions on their face,” Mr. Kmiec said. “This is a little bit of a retreat from Stenberg in that it’s calibrating the balance between the woman’s liberty interest and the state’s ability to regulate abortion, and it is calibrating it more finely than it has ever done before.”

Looming over the court’s decision in Ayotte v. Planned Parenthood are several state laws prohibiting so-called partial birth abortions.

Citing Stenberg v. Carhart, courts have struck down each of the laws as unconstitutional. The Bush administration has consolidated the cases into Gonzales v. Carhart and requested that the Supreme Court return to the issue again. The Supreme Court has rejected review as recently as January 6 and will again consider whether to take it up on Friday.

“Four justices could come from either side on this question,” Mr. Kmiec said. “The side that is generally friendly to abortion right could all vote for review on the supposition that the partial-birth case doesn’t need to be rethought. But I think it’s Justice O’Connor’s disposition to not leave the court in a blaze of controversy, so I think in all likelihood that she will be arguing in this internal conference to not take the case and to allow for further deliberations in the lower court.”

During his confirmation hearing, Chief Justice Roberts said he intended to bring the court together on issues that have caused splits in the past. Mr. Forsythe said the unanimous decision in Ayotte v. Planned Parenthood bore the marks of such an effort.

“I think it was an internally politically deft decision,” he said. “But that doesn’t mean this kind of unity is going to continue.”