Bishop Thomas J. Olmsted of Phoenix is being criticized by religious lawyers and medical ethicists for his declaration that a nun had excommunicated herself by advising that a seriously ill woman could have an abortion.

In an international debate raging in religious magazines and on the Internet, experts say the bishop failed to appreciate the circumstances that led to Sister Margaret McBride's decision as an administrator at St. Joseph's Hospital and Medical Center in Phoenix.

Olmsted declared McBride had excommunicated herself by "procuring," or bringing about, an abortion, and anti-abortion groups have assailed the nun.

But one church lawyer declared McBride's excommunication "null and void" because there was a lack of clarity over the circumstances surrounding the nun's decision.

The theological debate centers on two key issues. One is the circumstances of the medical procedure and whether it should be considered a treatment for an illness or a procedure intended to end the life of a fetus. The church would consider the latter to be an abortion.

The second is whether McBride believed she was acting within the ethics of the Catholic Church, which puts emphasis on whether a person knowingly and willingly violates church law.

One thing most people seem to agree on is that McBride, in her role as a hospital administrator, did not approve a standard abortion. The circumstances at St. Joseph's involved a woman who was so seriously ill that continuing her pregnancy could have killed her.

The 27-year-old woman, who had four other children, suffered from pulmonary hypertension and agreed to doctors' recommendation that she terminate the pregnancy only after it became clear to her that her life was in danger. McBride, as head of the hospital's ethics committee, took part in the decision with doctors, the patient and the mother's family.

The procedure took place in November but became public only in May after The Arizona Republic wrote about it. None of the people directly involved have been willing to discuss it.

According to a May 10 letter from the hospital's parent company, Catholic Healthcare West, McBride justified the procedure because the direct intent was to save the mother's life, not to end the pregnancy which, under Catholic teaching, is known as the principle of double effect.

Under "double effect," the death of a fetus is allowable as a secondary effect of required surgery.

Nancy Northup of the Center for Reproductive Rights, a group that uses legal means to promote contraception and birth control, has argued that pregnant women should not use Catholic hospitals because they could be compromised by church rules.

Cathleen Kaveny, a law professor at Notre Dame University who focuses on the intersection of law and morality, pointed out in Commonweal Magazine that McBride's intention meant the procedure "wasn't an 'abortion' " in the sense the procedure is prohibited by Catholic moral teaching, despite the "foreseen, terrible and unwanted side effect of causing the baby's death."

The St. Joseph's case was more like cases of uterine cancer or ectopic pregnancies, in which Catholic theology approves removing the diseased organs even if a fetus resides inside them, the Rev. Kevin O'Rourke, a professor of bioethics at Loyola University-Chicago and consultant for Catholic hospitals, wrote in America, a Jesuit magazine.

O'Rourke also argued that McBride must not have "knowingly and willingly" violated church law, making the excommunication "questionable."

But Gerard Nadal, a microbiologist who writes a blog, "Coming Home: Science in Service of the Pro-Life Movement," said that Catholic moral teaching never permits illicit means to reach a good end.

Because no diseased organ was treated, McBride could not be spared punishment, he said.

In the conservative Catholic journal First Things, Michael Liccione said the key issue is what role McBride's conscience played in her decision.

He asked whether excommunication made sense if she made her decision in good faith as a well-informed Catholic.

"The question is whether (Olmsted was) indeed right, and that is not clear even to some orthodox Catholics," wrote Liccione, who has taught theology and philosophy at Catholic universities.

He said it may not be possible to excommunicate someone for doing something they believe to be fully in accord with Catholic principles.

On the other hand, if the bishop is correct, that would mean McBride's conscience is "ill-formed - hard to believe for a religious person for 40 years - and that she had no excuse for making the wrong decision," Liccione writes. "The bishop's ability to make such a confident judgment in this case seems very unclear-to me and to many others."

Jesuit canon lawyer Ladislas Orsy of Georgetown University argued that there is such a lack of clarity that the excommunication is "null and void."

He said in a letter to the Tablet, a British Catholic newspaper, that excommunication requires "a deliberate act of defiance."

He also argued that McBride's role in the case indicates she did not "procure" the abortion, as required for excommunication under church law.

Church law, Orsy said, requires that the benefit of the doubt go to the accused. "The conclusion is compelling: to say the least, it is highly doubtful that Sr. Margaret acted out of malice aforethought, or that she actively procured an abortion," he wrote.

"Hence, she could not have been automatically excommunicated. The declaration of the excommunication by the local bishop, therefore, is null and void."

But Edward Peters, a canon lawyer with a seminary in Detroit, said the abortion could not have taken place without McBride's approval. Therefore, he said, as a necessary part of the procedure, the bishop acted properly.

Olmsted has threatened to remove his endorsement of all three Valley hospitals operated by Catholic Healthcare West - St. Joseph's, Mercy Gilbert Medical Center and Chandler Regional Hospital - because it does not force hospitals to follow the church's ethical and religious directives.

Neither McBride, her religious order, the Sisters of Mercy, nor the hospital has commented on the matter.