But that all changed in the early '70s, when Democratic politicians first figured out that the powerful abortion lobby could fill their campaign coffers (and attract new liberal voters). Politicians also began to realize that, despite the Catholic Church's teachings to the contrary, its bishops and priests had ended their public role of responding negatively to those who promoted a pro-choice agenda.

In some cases, church leaders actually started providing "cover" for Catholic pro-choice politicians who wanted to vote in favor of abortion rights. At a meeting at the Kennedy compound in Hyannisport, Mass., on a hot summer day in 1964, the Kennedy family and its advisers and allies were coached by leading theologians and Catholic college professors on how to accept and promote abortion with a "clear conscience."

The former Jesuit priest Albert Jonsen, emeritus professor of ethics at the University of Washington, recalls the meeting in his book "The Birth of Bioethics" (Oxford, 2003). He writes about how he joined with the Rev. Joseph Fuchs, a Catholic moral theologian; the Rev. Robert Drinan, then dean of Boston College Law School; and three academic theologians, the Revs. Giles Milhaven, Richard McCormick and Charles Curran, to enable the Kennedy family to redefine support for abortion.

Mr. Jonsen writes that the Hyannisport colloquium was influenced by the position of another Jesuit, the Rev. John Courtney Murray, a position that "distinguished between the moral aspects of an issue and the feasibility of enacting legislation about that issue." It was the consensus at the Hyannisport conclave that Catholic politicians "might tolerate legislation that would permit abortion under certain circumstances if political efforts to repress this moral error led to greater perils to social peace and order."

Father Milhaven later recalled the Hyannisport meeting during a 1984 breakfast briefing of Catholics for a Free Choice: "The theologians worked for a day and a half among ourselves at a nearby hotel. In the evening we answered questions from the Kennedys and the Shrivers. Though the theologians disagreed on many a point, they all concurred on certain basics . . . and that was that a Catholic politician could in good conscience vote in favor of abortion."