Abortion continues to overshadow all else in the consideration of U.S. Supreme Court replacements. Nevertheless, Chief Justice John Roberts quite prudently declined to tell the Senate Judiciary Committee his view of any future abortion cases.

As a matter of judicial ethics, Roberts could not prejudge. All previous cases, said Roberts, including those about abortion, "carry weight," but he noted that none are immune from reversal or limitation. Future controversies simply must be judged on the specific facts of each case and the Constitution.

While Roberts appropriately declined to get into the next abortion case on the court's docket, a closer look at the dispute in "Ayotte vs. Planned Parenthood of Northern New England" suggests that a pro-abortion outcome is far from certain. Ayotte concerns the constitutionality of New Hampshire's parental notification law. It precludes an abortion on a minor until at least 48 hours after written notice to a parent, unless the abortion is necessary to avoid the minor's death, a parent indicates that approval has been given or the minor goes to court and obtains a so-called "judicial bypass."

The lower federal court invalidated the law because it lacked a "health exception" and by applying a standard of review that biases the outcome.

Is this consistent with past jurisprudence?

Maybe not. Yes, the Supreme Court has demanded a broad health exception, even one including mental distress. This is why many pro-life advocates argue that judges effectively are allowing abortion on demand at any point in a pregnancy.

But perhaps a circumspect new member of the high court will not be satisfied with continuing this charade. After all, the court also has said that abortion can be outlawed post-viability, and shouldn't faithful adherence to precedent --- decided cases --- count for at least that much?

Even assuming the continuing insistence upon a sweeping health exception, assuredly a new justice would carefully examine the specific facts of the case. Doing so reveals that the New Hampshire parental notice requirement can effectively be waived by a judge, including presumably a judge sympathetic to a health claim.

Where then is the unconstitutionality, especially since the record establishes that minors have access to the courts 24/7?

The lower court held this pliable parental notice limitation to be unconstitutional on its face, under all circumstances. Why? Because, the lower court asserted, it could contemplate the possibility of a judge being slow to respond and thus creating an undue burden on the abortion right.

But here again, new eyes on the Supreme Court might well recall an elemental precept of constitutional jurisprudence: A facial challenge to a legislative act is the most difficult challenge to mount successfully since the challenger must establish that no set of circumstances exists under which the act would be valid. The fact that a legislative act might operate unconstitutionally under some conceivable set of circumstances is insufficient to render it wholly invalid.

The pro-abortion side in the New Hampshire case says this general rule of constitutional adjudication --- which soundly keeps judges from issuing rulings that are broader than necessary or being insufficiently respectful of legislative policies --- shouldn't apply.

This is special pleading. It suggests, as Justice Antonin Scalia has written, the existence of some "ad hoc nullification machine" that pushes aside whatever settled doctrines stand in the way of the favored abortion practice.

Don't misunderstand, the law in this area is anything but clear; it has divided the lower courts. That was reason enough for Roberts to say little. Yet, when the facts and record are examined, they suggest the abortion lobby didn't oppose Roberts because he is incapable of measured and impartial study, but because he is.

Douglas W. Kmiec is dean of Columbus School of Law at The Catholic University of America in Washington, and a monthly columnist for Catholic News Service.