We immediately encounter the question of what beings we should classify as "persons" for purposes of the duty not to kill persons

the official teaching of the Holy See of the Roman Catholic is unequivocal in its opposition to the use of embryos as means. For one who holds that we should treat every embryo as a person for purposes of the duty not to kill, embryo-destructive experiments could gain justification only if it were argued that it is sometimes permissible to kill some persons in order to help other persons, and that is an uphill argument within any moral view.

The late 1960s and early 1970s saw numerous states either repeal of modify their abortion laws, making the procedure much more accessible to American women. Abortion rates skyrocketed, and once again, studies estimated that an abortion occurred for every four live births in the United States.

Religious groups led the protests, with both the Catholic Church and several Protestant denominations denouncing abortion as immoral and sinful. Many Americans also objected to abortion on nonreligious grounds, arguing that abortion at any stage of a pregnancy was nothing short of murder.

Although the Court was generally conservative, it held that a woman's right to end an unwanted pregnancy in the first trimester was protected by the First Amendment's implicit protection to the right to privacy, but that after the first trimester, the state had an interest in protecting the growing fetus on the basis that the fetus was viable, or had the potential to live outside the womb. The decision touched off a hailstorm of controversy in the United States and prompted the formation of two movements: the pro-choice movement (which supports Roe v. Wade and a woman's right to choose to have an abortion) and the pro-life movement (which denounced Roe and decries abortion as murder).

In 2003, Congress passed and President George W. Bush signed the Partial-Birth Abortion Ban Act, which makes it a crime for doctors to perform the procedure, which is also known as intact dilation and extraction.

Most likely, the majority of Americans fall somewhere in between these two opinions, accepting abortion in some cases but not in others. The pro-life movement is split between those who object to abortions under any circumstances and those who would allow it in the case of rape, incest, or a threat to the mother's life if the pregnancy is carried to full term.

The pro-choice movement is similarly split between those who insist on abortion-on-demand at any stage of a pregnancy and those who adhere to the position articulated in Roe, whereby abortion is allowed only up to the point of viability for the fetus.

The more absolute pro-choice advocates, on the other hand, deny that the fetus is a person, entitled to the rights and protections of a fully developed human being, until it has been born, as it is dependent on another human life, its mother's, for its existence. Ultimately, the question of when individual human life begins does not lend itself to scientific proof. It is a matter of philosophical or moral belief and is therefore particularly difficult to debate.

Pro-choice advocates argue that abortion is preferable to bringing children into the world when the parents either cannot or will not nurture and provide for them. There are already too many children condemned to a life of poverty or abuse, they say. Many pregnant women and their families are either economically or psychologically unable to care for any more children. For them, abortion is the only humane alternative.

Furthermore, adoption, not abortion, is the solution for parents who feel themselves unable to support or protect their own children.

In recent years, radical activists on the pro-life side have taken to increasingly extreme forms of civil disobedience to stop what they consider the killing of unborn children. Such groups as Operation Rescue have tried several tactics to dissuade women from entering clinics where abortions are performed, ranging from quiet argument to shouting and blocking entranceways. More extreme activists have attempted to intimidate physicians specializing in abortion, harassing them in a variety of ways, both in person and over the telephone.