THE ANTI-ABORTION forces have a lot to smile about. Now that their best ally has been returned to the White House, they need only wait for two of those nasty old liberal Supreme Court justices to drop dead, and the evil Roe v. Wade abortion decision of 1973 will finally be vanquished.

But they won't be smiling for long, though. Their battle will have only just begun. In formulating new abortion laws, they will be forced to answer a variety of difficult legal and ethical questions.

And when they look at these questions, the movement will be forced to determine whether preserving "prenatal life" is truly its first priority. The rest of us will see how "pro-life" the pro-lifers really are.

One point is clear: the pro-lifers will not simply allow a return to the century-old pre-Roe abortion state abortion laws. As transcripts of state legislatures and state court decisions show, these laws were developed not to protect prenatal life, but to protect the health of pregnant women, as abortion was then a dangerous procedure. In Texas, abortion statutes provided that pregnant women could not be prosecuted either for attempting abortion themselves or for allowing abortions to be performed on them; only doctors were subject to prosecution.

Moreover, the state laws did not incorporate the cornerstone of the pro-life argument: that life begins at conception. The New York abortion statutes, which were prototypes for many other state laws, distinguished between the abortion of "quickened" fetuses (those capable of locomotion in the womb) and the abortion of "pre-quickened" fetuses: the first case was treated as second-degree manslaughter, the second as a misdemeanor.

TODAY'S PRO-LIFE movement does not seek merely to make abortion a crime. It wants to make into law its beliefs that life begins at conception and abortion, therefore, is murder. On that score, pro-lifers will have to start from scratch.

Starting from scratch will present a serious problem to these folks, who are used to arguing soley from a moral standpoint. Abortion may or may not be morally equivalent to murder, but considerations arising from the nature of the relationship between the fetus and the pregnant woman require a legal distinction.

For example, would pro-lifers advocate treating abortion as premeditated, first-degree murder--even if there were a death penalty involved? Obviously, treating abortion as any sort of murder would implicate both-abortionists (as murderers) and pregnant women (as accomplices, at least). But would fathers be legally culpable as well? Their roles in creating unwanted fetuses are at least tangentially related to the demise of those fetuses, so it seems they should also be held somewhat responsible. But what if the father of an aborted fetus had tried to prevent its abortion? What if it were uncertain who the fetus's father was?

The questions get even stickier when considering the issue of exceptions to the rule. One of the main reasons the Supreme Court overturned the Texas abortion law in Roe was that the exception for "saving the life of the mother" was unconstitutionally vague. If abortion is murder, what constitutes self-defense? Must the woman be in actual danger of dying if she carries the child to term, and how sure of this must her doctors be for an abortion to be legally permissible?

What if the woman will only be permanently physically handicapped if forced to bear the child?

What if she will be physically unharmed, but emotionally scarred?

And isn't that why most women have abortions in the first place?

BECAUSE OF this confusion over where to draw the line, there are some pro-lifers who would advocate no exception for self-defense. But if they are going to impose such a rigid and dogmatic standard, which would mean the death of the mother, they must show why abortion is worse than murder.

There is also the question of a rape exception. Pro-lifers who oppose it must justify the use of victims' bodies as vessels which, as a result of a traumatizing, violent crime, produce unwanted offspring.

Moreover, pro-lifers who favor a rape exception face even more complex questions, because they would only allow abortion following the rapist's conviction. But what if the woman could not positively identify her assailant? Or if she chooses not to prosecute? Or if the case drags on for more than nine months?