PIP: This article presents the history and grounds of the official position of the Roman Catholic Church that abortion under any circumstances, including abortion to save the life of the mother, should be prohibited. After an introduction that deplores the lack of mercy shown to killers of abortionists while Catholic priests threatened by pro-abortion forces are not offered protection, the article traces the historic development of the Catholic abortion policy and rebuts arguments that abortion was permitted in the early Christian Church. The next section explains Catholic views on the personhood of a conceptus and refutes the contentions of Joseph Donceel that early abortion should be permitted because of uncertainty about the nature of the conceptus and the possibility of delayed animation. The fourth section of the paper debates the points raised by Susan Teft Nicholson who maintains that the Catholic position regarding abortion rests on the Church's animosity towards sexual pleasure. The paper goes on to criticize Nicholson's claims that the Roman Catholic position on abortion is inconsistent with the Church's own understanding of the Principle of Double Effect because the Church fails to allow abortion in many cases where it would be permissible under the Principle. Section 6 describes the underlying motive of the Roman Catholic Church's abortion position as an attempt to protect the innocent fetus from deliberate death and to justify the Church's application of protection from deliberate killing to those who are innocent of aggressive action. This discussion is followed by a justification of the Church's prohibition of abortion in cases of aggression, such as the aggression ascribed to a fetus when a pregnancy imperials the life of a mother. It is concluded that the US will likely legalize suicide and mercy killing as it has the killing of innocent fetuses who are probably ensouled with personhood and are not formal aggressors.