Since the Catholic Church views abortion as gravely wrong, it considers it a duty to reduce its acceptance by the public and in civil legislation. While it considers that Catholics should not favour abortion in any field, it recognises that Catholics may accept compromises that, while permitting abortions, lessen their incidence by, for instance, restricting some forms or enacting remedies against the conditions that give rise to them. It is accepted that support may be given to a political platform that contains a clause in favour of abortion but also elements that will actually reduce the number of abortions, rather than to an anti-abortion platform that will lead to their increase.Frank K. Flinn, J. Gordon Melton (editors), Encyclopedia of Catholicism (Facts on File 2007 ), p. 5

United States

Before the 1973 Roe v. Wade Supreme Court decision that opened the door to the legalization of abortion, the right-to-life movement in the U.S. consisted of lawyers, politicians, and doctors, almost all of whom were Catholic. The only coordinated opposition to abortion during the early 1970s came from the United States Conference of Catholic Bishops and the Family Life Bureau, also a Catholic organization. Prior to Roe v. Wade decision, abortion was not a high priority for Catholic bishops in the United States. Neither was abortion a prominent issue in American politics prior to Roe v. Wade. It was not a major platform plank for either party in the 1968 and 1972 elections.

In the 60s and early 70s, there was a shift as a number of Catholics and Southern whites abandoned their traditional affiliation with the Democratic party and began to support the Republican party. This shift is evidenced by the fact that Nixon received only 33% of the Catholic vote in the 1968 election compared to 52% in 1972. As a group, Catholics represented a quarter of the nation's electorate and were now one of the nation's largest swing groups. Both parties began to aggressively woo both the Catholic voters. Although the Catholic hierarchy could not dictate who Catholics voted for, they did have a substantial influence over the faithful in their dioceses. Politicians were aware that the bishops could employ significant time, energy and money to support the issues that were important to them. From their perspective, the bishops were eager to regain some of the influence that their predecessors had wielded in the earlier part of the 20th century.

After Roe v. Wade, the involvement of the Catholic hierarchy in American politics increased to an unprecedented level, with bishops devoting more time, energy and money to the issue of abortion than any other single issue. The substantial role of the Catholic Church in the abortion debate has received much attention in the American media .

Mobilization of a wide-scale anti-abortion movement among Catholics began quickly after the Roe v. Wade decision with the creation of the National Right to Life Committee (NRLC). The NRLC also organized non-Catholics, eventually becoming the largest anti-abortion organization in the United States. Connie Paige has been quoted as having said that, "[t]he Roman Catholic Church created the right-to-life movement. Without the church, the movement would not exist as such today."

In the two years following the Roe v. Wade decision, U.S. bishops focused on passage of a Human Life Amendment to the U.S. Constitution which would ban abortion.

A Pastoral Plan for Pro-Life Activities In November 1975, the National Conference of Catholic Bishops (NCCB) and the United States Catholic Conference (USCC) published a document titled "A Pastoral Plan for Pro-Life Activities" that outlined a strategic plan for anti-abortion activities by members of the Catholic clergy and laity. Laurence Tribe describes the document as "an extraordinary organizational blueprint for political action." The plan called for a "comprehensive pro-life legislative program" that would push for "passage of a constitutional amendment providing protection of the unborn child to the maximum degree possible."

To accomplish its goals, the plan called for the formation of committees at the state level that would coordinate the political efforts in the dioceses and congressional districts of that state. Each diocese was to have an anti-abortion committee that would push for the passage of a "constitutional amendment to protect the unborn child." The plan also called for the creation of an "identifiable, tightly-knit and well-organized pro-life unit" in each congressional district to track voting records of elected officials vis-a-vis abortion and to mobilize resources for political action.

Despite the concern of some bishops that the Pastoral Plan was narrowly focused on just the issue of abortion, the plan was adopted in 1975 and subsequently re-approved in 1985 and 2001.

1976 presidential election

Abortion became an issue early on in the race for the 1976 Democratic presidential nomination. Senator Birch Bayh, who had chaired hearings on a constitutional amendment to ban abortion, finally broke his silence on the issue and came out against the passage of such an amendment. Bayh's stance opposing the amendment was soon echoed by Frank Church and Sargent Shriver, a practicing Catholic.

The Democratic Party began to fracture over anti-abortion and abortion rights lines. Anti-abortion Democrats sought a candidate sympathetic to their stance on the constitutional amendment. However, conservative Democrat George Wallace declared his support for such an amendment. Laurence Tribe attributes Jimmy Carter's victory in the Iowa caucuses to his having "fudged" his position on abortion although Carter publicly denied having done so. On the Republican side, Ronald Reagan declared his support for a constitutional amendment that would effectively ban abortions. Although President Ford won the nomination of his party, Reagan's supporters were able to push through a plank in the party platform that called for a "constitutional amendment to restore the protection of the right to life of unborn children."

The Democratic party platform included a plank that asserted that it was "undesirable to attempt to amend the U.S. Constitution to overturn Roe v. Wade. In an attempt to mollify the displeasure of U.S. bishops, Carter arranged a meeting with six bishops to clarify his position that, although he had not yet seen a specific phrasing that he could support, he remained opposed to abortion and pledged that he "would never try to block" an amendment banning abortion. This stance failed to placate the bishops. Attempting to capitalize on Carter's failure, President Ford signaled his agreement with the bishops' position by inviting the NCCB/USCC's Executive Committee to the White House. After the meeting, the bishops declared that, while they were not totally satisfied with Ford's position, they were encouraged by it and that they felt that "support for the concept" of a constitutional amendment was more important than agreement on a "specific kind of amendment."

However, in Laurence Tribe's estimation, abortion played a less significant role in the general election than it had in the primaries. When asked to rank fifteen issues in order of importance, voters ranked abortion as fifteenth. According to exit interviews conducted by CBS News, the Catholic vote wound up favoring Carter by 54% to 44%, a wider margin than the general electorate which favored Carter over Ford by just 50% to 48%.

1980 presidential election During the 1980 presidential election, Ronald Reagan made the anti-abortion cause a key issue in his campaign. He endorsed a constitutional amendment banning abortion, promised to appoint anti-abortion judges to the federal bench and prohibit the use of federal funds for abortions except where necessary to save the life of the mother. According to the results of exit interviews published in the New York Times, Catholics favored Reagan over Carter by 51% to 40%, a margin very similar to that of the general electorate.New York Times, November 9, 1980, p. 28

1984 presidential election

By 1984, the Republican party was fully aligned with traditional religious values including the anti-abortion movement. Whereas Catholics had generally voted Democratic until the late 1960s, this traditional affiliation had diminished by 1984 to a weighting in favor of the Republican party with abortion being one of the key drivers of the shift.

Sharp criticism from Church authorities put Democratic vice-presidential candidate Geraldine Ferraro on the defensive throughout the entire campaign, with abortion opponents frequently protesting her appearances with a level of fervor not usually encountered by Catholic, male, pro-abortion rights candidates such as Mario Cuomo and Ted Kennedy.Light and Lake, The Elections of 1984, pp. 103, 107–108. Ferraro was criticized by name by Cardinal John O'Connor, the Catholic Archbishop of New York, and James Timlin, the Bishop of Scranton, for misrepresenting the Catholic Church's position on abortion.Prendergast, The Catholic Vote in American Politics, pp. 26, 187. In a 1982 briefing for Congress Ferraro had written that, "the Catholic position on abortion is not monolithic and there can be a range of personal and political responses to the issue." Cardinal O'Connor publicly criticized Ferraro for making this statement. After several days of back-and-forth debate in the public media, Ferraro finally conceded that, "the Catholic Church's position on abortion is monolithic" but went on to say that "But I do believe that there are a lot of Catholics who do not share the view of the Catholic Church".

The group Catholics for a Free Choice placed an October 7, 1984, full-page ad in The New York Times titled "A Catholic Statement on Pluralism and Abortion". The advertisement stated that "direct abortion ...can sometimes be a moral choice" and that "responsible moral decisions can only be made in an atmosphere of freedom from fear of coercion."

Debate within the Catholic hierarchy