Given such unanimity in the doctrinal and disciplinary tradition of the Church, Pope Paul VI was able to declare that this tradition [regarding abortion] is unchanged and unchangeable. Therefore, by the authority which Christ conferred upon Peter and his Successors, in communion with the Bishops – who on various occasions have condemned abortion and who in the aforementioned consultation, albeit dispersed throughout the world, have shown unanimous agreement concerning this doctrine – I declare that direct abortion, that is, abortion willed as an end or as a means, always constitutes a grave moral disorder, since it is the deliberate killing of an innocent human being. This doctrine is based upon the natural law and upon the written Word of God, is transmitted by the Church’s Tradition and taught by the ordinary and universal Magisterium. (Evangelium Vitae, § 62 Pope John Paul II)
According to Catholic theology, a teaching of the “ordinary and universal magisterium” is infallible if it is taught by all Bishop dispersed throughout the world, as long as they all teach it in a definitive and authoritative manner. Before writing Evangelium Vitae, Pope John Paul II surveyed every Catholic bishop in the world asking whether they agreed that murder, directly-willed abortion, and euthanasia were immoral, and they all agreed that they were. To make this connection clear, the pope concluded each of these passages in Evangelium Vitae with a reference to the “ordinary and universal magisterium” and a footnote that cited Lumen Gentium§ 25.
The current Prefect of the Congregation for the Doctrine of the Faith, William Levada, wrote in 1995 that Evangelium Vitaes teaching regarding abortion was an infallible teaching of the ordinary magisterium.
Among the Catholic theologians who have written about infallibility, nearly all agree that these three statements constitute infallible teaching. These theologians include “liberals” (Richard Gaillardetz, Hermann Pottmeyer), “moderates”, and “conservatives” (Mark Lowery, Lawrence J. Welch).
Not sure where I found this info, sitting on my computer, copied it from somewhere. Hope this helps.