Abortion foes who are counting on the U.S. Supreme Court to make the practice illegal in Arizona may be rudely surprised.

Last month, the nation's high court agreed to review a Missouri law that restricts the right to abortion. Advocates on both sides of the issue believe the justices will use this case to revisit--and possibly overturn--their historic Roe v. Wade ruling, which declared that most abortions are none of the government's business. That 1973 case made every state's anti-abortion laws unenforceable.

Arizona lawmakers never took those laws off the books. That means the day Roe is overturned, police and prosecutors in Arizona will be free to begin arresting doctors and pregnant women and closing clinics.

But pro-choice forces believe they may have an ace in the hole, all because of a battle over the legal right of an elderly Tucson woman to die.

Mildred Rasmussen had led an independent life until being admitted to a county-owned nursing home in Tucson in 1979 at age 64. After admission, however, her condition deteriorated as she had three strokes and was suffering from a degenerative disease. Rasmussen got to the point where she had to be tube-fed. She was unable to care for herself and remained in bed, curled in a fetal position.

Doctors--with the implicit consent of what little family she had--ordered that if she became ill, she was not to be hospitalized. That meant certain diseases, such as pneumonia, gangrene and urinary tract infections, were to run their natural course without treatment, probably culminating in her death. The doctors also ordered that, in case of respiratory or cardiac failure, she was not to be resuscitated.

The issue would have rested there had not Robert Fleming, the Pima County public fiduciary, filed suit, asking to be appointed Rasmussen's legal guardian. The goal was to permit the removal of the feeding tube, allowing her to die more quickly.

A judge ordered a hearing and also appointed a separate individual to represent Rasmussen's interests. That person challenged the petition to remove the feeding tube but was rebuffed by a lower court. While the case was on appeal, Rasmussen died of complications following pneumonia.

Despite her death, the Arizona Supreme Court took the case of Rasmussen v. Fleming to rule on the legal issues. The high court said it not only had to decide whether the public fiduciary could act to remove the feeding tube, but, more important, whether Rasmussen herself had a legal right of privacy to refuse medical treatment.

Chief Justice Frank Gordon, who wrote the 1987 opinion, noted that there is no explicit federal right of privacy. But Gordon pointed out that the Arizona Constitution--unlike its federal counterpart--has a specific right to privacy built right in: Article 2, Section 8, states that "no person shall be disturbed in his private affairs, or his home invaded, without authority of law."

Gordon acknowledged that he and his colleagues usually reserve this constitutional protection for criminal defendants who are claiming illegal search and seizure. But he maintained that it also applies to other forms of privacy.

"An individual's right to chart his or her own plan of medical treatment deserves as much, if not more, constitutionally protected privacy than does an individual's home or automobile," Gordon wrote.

If the message of the court ruling was not clear, Gordon's court colleague Stanley Feldman brought the lesson home.

Feldman, in an article last year in the Arizona State Law Journal, said he believes the Arizona Supreme Court is entitled to protect various kinds of privacy. Feldman didn't specifically say the state's high court will extend this right of privacy to protect legalized abortion. But partisans on both sides of the issue think that's exactly what some of the justices have in mind.

Beryl Sweet, lobbyist for Arizona Right to Choose, says lawyers for her organization are studying this approach as a fallback position if Roe is reversed.

"We are going to have to figure out how we are going to test this" in the state courts, Sweet says. She believes the idea of protecting legal abortion under the state constitution is not so far-fetched, citing a ruling in a recent California case that the right to abortion is protected by the right to privacy in that state's constitution.

Scottsdale Republican Representative Jim Skelly, the prime mover of most of the anti-abortion bills in the Arizona State Legislature, says he wasn't terribly concerned at first about the state Supreme Court's ruling in the Rasmussen case. But that was before he saw Feldman's article and recognized where the court might be heading--or, at least, where Feldman thinks the court is heading.

"What I see," says Skelly, "is the potential that, despite the overturning of Roe v. Wade, the Arizona court could still declare abortion to be legal."

Just-retired state Supreme Court Justice William A. Holohan questions how far the Rasmussen case can be used to protect abortions. Holohan was the main opponent of activists like Feldman. Yet Holohan went along with the majority in upholding Rasmussen's right to refuse medical treatment on the grounds of personal privacy. Extending that logic to include abortion, however, might be taking it a step too far, Holohan argues.

Gordon noted in his written ruling that there was no third party in the Rasmussen case--she had no children and her three siblings had agreed with the decision of the doctor and the public fiduciary to terminate treatment.

But in an abortion case, Holohan says, the court would have to decide whether the fetus is a legitimate third party whose interests also have to be considered.

"What you're really talking about in this whole thing," says the former justice, "is competing interests: a woman's right to treat her body as she wants as opposed to when the fetus has a right to be protected."

Skelly argues that the protection of abortion as a matter of privacy could not possibly be what the framers of the Arizona Constitution had in mind in 1912. He points out that Arizona has had anti-abortion laws dating back to Territorial days, with the roots of the current--but unenforced--statute traced directly back to a 1901 law.

The laws still on the books in Arizona make it a felony for anyone to perform an abortion unless it is necessary to save the life of the mother. The penalty is from two to five years in prison. Another law makes felons of women who solicit an abortion, with a similar penalty. Finally, there is a statute that makes it illegal for anyone to advertise abortion services.

If Roe is overturned, arrests for violation of Arizona's existing anti-abortion laws are likely to follow. At that point, one of two things likely will happen. A doctor charged with performing an abortion will argue that the anti-abortion laws violate rights granted by the Arizona Constitution. The Rasmussen case would be cited as a precedent. It could take years for such a case to wind its way through the court system.

A different scenario is likely if a woman is charged with seeking an abortion or a prosecutor attempts to stop a pregnancy from being terminated. Because of the limited time available--and the fact that an abortion becomes more dangerous the longer a woman waits--lawyers would seek an immediate injunction from the courts, barring police from enforcing the law. That could result in a state Supreme Court hearing on the question within days.

Sweet says she has tried for several years to get lawmakers to take the anti- abortion statutes off the books. But she has had no takers.

"Very few people are willing to go out on a limb on this one," she says, because they would be risking the wrath of the politically active anti-abortion groups "over an issue that, at least today, is moot."

Anyway, Sweet says, if the U.S. Supreme Court overturns the Roe decision, the pro-choice forces in Arizona may have a better chance of arousing the public if performing--and seeking--an abortion is a criminal offense. "We might get more mileage," she says, "by having a law on the books that is unconscionable, like throwing a woman in jail."

"What I see," says Skelly, "is the potential that, despite the overturning of Roe v. Wade, the Arizona court could still declare abortion to be legal."