No dogma has to be affirmed, nor anyone anathematized, nor the word “define” or “definition” be used for an infallible papal teaching – only that the Pope is handing down a certain, decisive judgment for the whole Church, that a point of doctrine on faith or morals is true and its contrary false. The words *ex cathedra *are never included.
Vatican II (Lumen Gentium, 25) reaffirms this teaching: “The Roman Pontiff, head of the college of bishops, enjoys this infallibility in virtue of his office, when, as supreme pastor and teacher of all the faithful – who confirms his brethren in the faith (cf. Lk 22:32) – he proclaims in an absolute decision a doctrine pertaining to faith or morals.”
**The three levels of teaching from Ad Tuendam Fidem are:
**1) Dogma – infallible (Canon #750.1) to be believed with the assent of divine and Catholic faith.
2) Doctrine – infallible (Canon #750.2) requires the assent of ecclesial faith, to be “firmly embraced and held”.
3) Doctrine – non-definitive (non-infallible) and requires intellectual assent (“loyal submission of the will and intellect”, Vatican II, *Lumen Gentium 25), not an assent of faith. See the Explanatory Note on ATF by the Congregation for the Doctrine of the Faith at
Contraception has been infallibly condemned both in *Casti Connubii *(Pius XI), 1930, and in Humanae Vitae (Paul VI), 1968.
The extraordinary Magisterium was in fact exercised as Dr David M. Gregson explains.
In Casti Connubii, Pius XI, declared “any use whatsoever of matrimony exercised in such a way that the act is deliberately frustrated in its natural power to generate life is an offense against the law of God and of nature, and those who indulge in such are branded with the guilt of a grave sin.” Casti Connubii, 56, 1930].
Pius XI in Casti Connubii, refers to the “doctrine handed down from the beginning without interruption” which fact alone makes it an infallible teaching according to the “universality of time” which argument was used also by Pius XII for the dogma of Our Lady’s Assumption (1950).
Furthermore, it is infallible because of the “universality of the present” — because Vatican II declared unequivocally that “In questions of birth regulation, the sons of the Church, faithful to these principles, are forbidden to use methods disapproved of by the teaching authority of the Church in its interpretation of the divine law.” Gaudium et Spes, 51; footnote 14 refers to “Casti Connubii” and further teaching by Pius XI and Paul VI]. So the bishops of the Church in Ecumenical Council, approved by the Pope, give this teaching.
In fact, *Casti Connubii *of Pope Pius IX, 1930, infallibly condemned contraception (#56) “as any use whatsoever of matrimony exercised in such a way that the act is deliberately frustrated in its natural power to generate life is an offense against the law of God and of nature, and those who indulge in such are branded with the guilt of a grave sin.”
Pope St John Paul II also firmly stated that the ban on contraception “cannot be questioned by the Catholic theologian,” much to the consternation of Father Charles Curran and his dissenting brethren.
 “Pope Warns Theologians not to Question Ban on Contraception.” The Wanderer, November 24, 1988, Page 1.