Dr. Julian De Lia pioneered an intricate laser surgery technique that he performs on unborn babies who have twin-transfusion syndrome.

De Lia, an associate professor at the University of Utah School of Medicine, developed the high-risk, innovative technique to fuse shut placenta cells between twins when the blood flows just one way. Technically, the surgery is against Utah law, which prohibits experimentation on unborn children, except for genetic testing.The American Civil Liberties Union has filed suit challenging the abortion law, and in addition, the older law that prohibits experimentation. And in an amended complaint filed this week, 177 members of the American College of Obstetricians and Gynecologists have joined the suit. The association says the doctors fear prosecution under the criminal statute.

De Lia admits that according to a strict interpretation of the law, the surgery he performs might be considered illegal. But he says the U. Hospital's institutional review board approved the procedure. "I do exper mental surgery. But my experimental surgery is really on the placenta, not on the fetuses." The physician said he doesn't plan to worry about it, although he would rather go fishing than go to prison.

But Dr. David Green, a pediatrician and chairman of the University Hospital's ethics committee, said the law creates problems. Because of technology breakthroughs in the past decade, doctors are beginning to perform experimental surgery on fetuses to correct conditions that can get worse during pregnancy and delivery. Those same procedures, if performed after birth, might be considered routine. But they have high failure rates when performed while the fetus is in the womb.

"It would seem that if the point of the legislation is to ensure that fetuses survive, I would kind of assume that along with that people would want them to survive in a healthy way," Green said. "This (law) would sound kind of contrary to that."

Michele Parish, Utah director of the ACLU, said the law, using the club of prison sentences, transfers the practice of medicine to legislators. While the legislation might have been designed to stop abortions, it already has had a chilling effect on doctors.

"What seems reasonable is not necessarily what's legal," Parish said. "When you have a law that is so vague that doctors can't tell whether what they are doing is legal or not, then you have an unconstitutional law.

"If that law was to go into effect and be enforced, you could actually bring that practice of medicine to a screaming halt."

Howard Lundgren, an attorney, said with this statute Utah has adopted a wait-and-see attitude toward medical breakthroughs. "The problem is that everything that is part of technology was once an experiment.

"We're not saying we're ignorant of the law. We know there's a law and we know there's a crime. But we don't know what conduct constitutes a crime."

Dr. Keith Tolman is chairman of the U. Hospital's institutional review board, the group that approves all innovative treatments. He contends there is a difference between therapy and research. But he admits De Lia's surgery might fall between the two.

"There's obviously sort of a gray line, and the line is not well-defined by the law. Who knows how you make those decisions?"