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?

Last, but not least, there is the question of enforcement. Outlawing abortion will not significantly change societal attitudes--women who would have legal abortions today would still want illegal ones tomorrow. The pro-life movement will have to deal with that, and with the specter of abortion black markets and back-alley butchers. In practice, it just might be that the costs of abortion laws would far outweigh the benefits.

THERE'S A larger lesson to be learned here about attempts to incorporate morality into politics. It is not enough to say only that abortion is wrong, for our legal code isn't simply a list of "Thou shalt nots." The questions the abortion issue raises are perplexing enough in the realm of abstract morality, but trying to translate them into concrete legal doctrines requires a Hercules of jurisprudence. If arrogant abortion foes like New York Archbishop John J. O'Connor actually tried to answer these questions, they would realize that the issue isn't so clear-cut, and perhaps they would be more humble about making political pronouncements.

This is not meant to imply that people who believe abortion is wrong cannot act on the basis of their beliefs. They are morally obligated to do so. But they cannot claim that their arguments are based on anything other than morality, and because they quickly run into insurmountable legal dilemmas in answering the questions that come up, they must operate extra-legally.

If the pro-lifers simply attempt to change societal attitudes toward abortion through persuasion, they will not only have more credibility, but they will have more success. After all, once the issue of choice is removed, no one really likes abortion: it is physically excruciating and humiliating, often leaving permanent emotional scars. It only exists because women regard it as a lesser evil than bearing unwanted children.

The pro-lifers' first task, then, is to reduce the number of unwanted pregnancies. Complete mandatory programs of sex education and readily available birth control would go a long way toward achieving this end. Too many pregnancies result from sheer ignorance. If more teenagers were taught how to use contraceptives properly, fewer of them would fail to use them. If more teenagers were completely informed about the realities of abortion, fewer would regard it as an easy alternative. And if more teenagers were taught not merely how babies are made, but what the responsibilities of baby-making are, more would be able to make informed adult choices.

Contrary to The Rev. Jerry Falwell's protestations, sex education does not endorse premarital sex; it merely recognizes that premarital sex exists. If the Moral Majority wants to prevent teenagers from having sex, they should fight not abortion or sex education--but the onset of puberty.

Of course, education alone won't prevent all unwanted pregnancies. Accordingly, another goal of the pro-life movement should be to make it easier for pregnant women to choose to bear their children.

Much of the motivation for abortion arises from the social stigma attached to unmarried pregnant women, especially peer pressure-prone teenagers. If those women were treated with concern and respect instead of being regarded as sinners, perhaps they would not be nearly as willing to have abortions.

Of course, institutionalized compassion throughout society would deprive demagogues like Falwell of a prime opportunity for moral posturing. But if pro-lifers' first priority really is the lives of fetuses, it is a price they will gladly pay.

Of course, changing society's attitudes overnight is impossible, and resorting to extra-legal means won't eliminate abortion entirely. But considering the difficulty of instituting and enforcing a legal prohibition of abortion, an extra-legal pro-life movement would probably be much more effective in preventing abortions without abridging anyone's freedom of choice. And to a true pro-lifer, preventing more abortions is all that matters.