A Fort Wayne teacher who claims she was fired from a Roman Catholic school for using in vitro fertilization to try to get pregnant is suing in a case that could set up a legal showdown over reproductive and religious rights.Emily Herx's lawsuit accuses the Diocese of Fort Wayne-South Bend and St. Vincent de Paul School in Fort Wayne of discrimination for her firing last June.Herx, 31, of Hoagland, Ind., said that the church pastor told her she was a "grave, immoral sinner" and that a scandal would erupt if anyone learned she had undergone in vitro fertilization, or IVF.The Roman Catholic Church shuns IVF, which involves mixing egg and sperm in a laboratory dish and transferring a resulting embryo into the womb. Herx said she was fired despite exemplary performance reviews in her eight years as a language arts teacher.Legal experts said Herx's case illustrates a murky area in the debate over separation of church and state that even the U.S. Supreme Court has failed to clearly address.Diocese officials said in a statement issued to The Associated Press on Wednesday that the lawsuit challenges its rights as a religious institution "to make religious based decisions consistent with its religious standards on an impartial basis." The U.S. Supreme Court ruled unanimously in January that religious workers can't sue their employers for job discrimination because anti-discrimination laws allow for a "ministerial exception." But the justices failed to define who was and who wasn't a religious employee."The Supreme Court didn't give us a kind of neat little on-off test as to who's a minister and who isn't," said Rick Garnett, associate dean and professor of law at Notre Dame Law School.In a similar case in Ohio, a federal judge last month gave the go-ahead for a trial in a lawsuit against the Archdiocese of Cincinnati by a parochial school teacher who was fired after she became pregnant through artificial insemination, which the church is also against. The archdiocese fired Christa Dias in 2010, saying the single woman violated church doctrine.U.S. District Judge Arthur Spiegel said in his March 29 ruling that the ministerial exception did not apply because Dias was a non-Catholic computer teacher with no role in ministering or teaching Catholic doctrine.However, Garnett said he believed the ministerial exception cited by the Supreme Court could be applied to most parochial school teachers."A lot of Catholic schools, including my own kids', every teacher brings the kids to Mass, is involved in sacramental activities. ... It's not just one teacher who teaches religion, religion is pervasively involved," Garnett said. "The key question is whether it would interfere with the religious institution's religious mission, its religious message, for the government to interfere in the hiring decision."Herx's attorney, Kathleen Delaney of Indianapolis, disagreed."She was not a religion teacher. She was not ordained. She was not required to and didn't have any religion teaching. She wasn't even instructed about the doctrine that she violated," said Delaney, noting the ultimate decision would be up to the courts.The school found out that Herx was using IVF because she told them about it when she used sick days for the treatments, according to the lawsuit. School officials didn't indicate until later that there was a problem, the lawsuit says.At the time, the school's principal told Herx, "You are in my prayers," and allowed her to take time off to receive treatments, according to court documents referenced in an ABC News report.Delaney would not say if Herx was able to get pregnant using IVF.The diocese said that teachers, even those such as Herx who aren't Catholic, are required by their contracts to abide by Catholic tenets and "serve as moral exemplars."Pope Benedict XVI as recently as February urged infertile couples not to use in-vitro fertilization or other forms of artificial procreation, which the church views as an affront to human dignity and the dignity of marriage.The church believes that procreation should be limited to marital sex, said Dr. John Haas, director of the National Catholic Bioethics Center in Philadelphia. Also, clinics routinely fertilize more eggs than are implanted, and extra embryos may be destroyed. The church believes those lives are sacred, Haas said."To have a child by in vitro almost invariably results in the death of a number of embryos as one works to bring one to term," Haas said Wednesday.Herx's lawsuit, filed Friday in U.S. District Court in Fort Wayne, alleges the diocese violated the Civil Rights Act and the Americans with Disabilities Act by discriminating against Herx based on gender and on infertility, which is considered a disability. The Equal Employment Opportunity Commission upheld Herx's complaint in January.