Although no one knows the precise number, it is estimated that 50,000 human embryos are in deep freeze at America's in vitro fertilization banks. If the Clinton administration and others have their way, those embryos not needed by infertile couples will move from the clinic freezer to the biotech lab for research funded by the federal government.

Among the many reasons offered in favor of human embryo research, two of them have become repeated most often. First, some argue that since surplus embryos are most likely to be destroyed, it is better to put them toward a good use. Second, others argue that our social obligation to seek cures for the chronically ill outweighs any moral commitment to embryonic life.

After fertilization and before implantation in the womb, a human embryo contains so-called stem cells, the building blocks for more than 200 cell types within a human body. The goal for such research is to manufacture new specialized cells for use by physicians. Such cells, for instance, could be employed to cure illness through implantation into diseased organs, stimulating the growth of new, healthy tissue.

Last November, after privately funded researchers cultivated stem cells taken from destroyed human embryos and aborted fetuses, the Clinton administration, some members of Congress, patient-advocacy groups, the for-profit biotech industry, and biotech researchers all began to lobby for federal funding for embryonic stem cell research. (Congress in 1995 banned federal funding for any research on human embryos that posed the risk of harm.)

The coming battle over research on human embryos promises to be a defining moment in bioethics and is a struggle that should engage those who value unborn life.

Serving the greater good? When ...