While even those most supportive of a woman's right to choose understand that a fetus does acquire fundamental human rights at some point relatively early in the third trimester, opponents of autonomous reproductive rights hold the position that personhood begins at the moment of conception (Mappes & Zembaty, 2008). This is the main source of legal controversy precisely because it reflects a religious belief defining human life as being created at the moment of fertilization (Mappes & Zembaty, 2008). While that is a perfectly acceptable belief within the framework of religious philosophy, it is a fundamental violation of the concept of separation of church and state to impose that belief on secular laws.

The First constitutional amendment prohibits both the establishment and the prohibition of religion by the government. Going back even further, religious freedom was one of the principle motivations of the original Settlers who left British rule, precisely because of their experiences under mandatory religious affiliation for centuries. Under modern Constitutional concepts and interpretations of the Supreme Court, the imposition of religious definitions of the beginning of life violates those fundamental principles where they influence laws that determined the rights of individuals who subscribe to different religious beliefs (Mappes & Zembaty, 2008).

Ethical Issues:

There are legitimate ethical...

The fully developed fetus and nearly fully developed fetus are clearly entitled to basic human rights by virtue of (1) their ability to sense pain and discomfort, and (2) their capacity to survive outside the womb. Prior to the stage where a fetus becomes sentient or capable of survival, there is no objectively valid basis for objecting to elective abortion (Mappes & Zembaty, 2008).
Contrary to religious beliefs, the mere act of fertilization has absolutely no objective moral significance simply because the zygote produced consists of only a small number of undifferentiated cells without any human form or function whatsoever. They merely have potential to develop further, very much like human sperm and unfertilized ova. Admittedly, the fertilized zygote does contain the full set of DNA required to define a complete human being, but so does every flake of dandruff or hair follicle that falls from a living person (Mappes & Zembaty, 2008).

The main ethical obligation to the unborn fetus is to avoid causing any physical pain or discomfort during the abortion procedure. That scenario arises anytime the physiological capability to sense pain develops before the decision to terminate a pregnancy, regardless of the reason or justification. Even a mother whose life would be threatened by delivering the infant has a moral obligation to minimize any conceivable pain to the fetus in the process.

Finally, fetal "viability" outside the womb is also a relevant issue although in modern times it is greatly dependent on medical technology and procedures. However, even survivability may no longer be as relevant a criterion because today, sophisticated medical approaches have pushed back survivability so much that mere "survivability" may no longer be as relevant a criterion (Mappes & Zembaty, 2008). Ultimately, abortion should be a private matter between a woman, her family, and her physician; the state has no justification for involvement outside of the regulation of specific medical issues and the protection of the fetus after the point that secular medical authorities determine that the fetus should be considered a person.