Although at the end of life the definition of death is the cessation of the function of the circulatory system, i.e. heartbeat and breathing, the beginning of life is different.
Although an embryo does not yet have a functioning circulatory system, “life” in halachic terms will have begun once the fetus is endowed with a soul. The Talmud relates that the soul is endowed at the fortieth day from conception. Hence, it is “alive” from that time forward, and to end that life when halachically impermissible, would be an act of murder according to Jewish law.
[Maimonides and the later commentaries explain, based upon a complicated Talmudic discussion, that such a murder would not be subject to judgment in a Beis Din, or rabbinic court of law, but is considered murder in the “Heavenly court.”]
This perspective has profound implications in medical ethics from a Jewish standpoint and forces us to look at the question of “pro-life” from a different vantage point than that of popular culture.
There are, however, times that from the standpoint of halacha, or Jewish law, that the cessation of the life of a fetus is permitted or even mandated, such as the mother’s life being in danger as a result of the pregnancy. The details of this obviously cannot be outlined in a column such as this and must be submitted to a competent halachic authority when such questions arise.
Rabbi Yerachmiel Fried