Sandro Magister has an interesting review of a book (the book is only available in Italian) on confessional practice and contraception in the Diocese of Padua in the early 20th-century:
… one constant guideline emerges from the solutions given by the diocese of Padua to cases of morality regarding contraception: that of employing the ‘theory of good faith’ taught by Saint Alphonsus Maria de Liguori. According to this theory, in the presence of a penitent who is suspected of committing contraceptive actions but appears unaware of the gravity of the sin and in practice incapable of correcting his behavior, it is best to respect his silence and take his good faith into account, absolving him without posing any further questions.
The Liguorian theory was dominant for many decades, not only in the seminaries and in the care of souls, but also in the guidelines given by the Holy See in the nineteenth and early twentieth centuries …
A change took place in 1931 with the publication by Pius XI of the encyclical ‘Casti Connubii.’ From then on, at the behest of the hierarchy, conjugal morality became a bigger part of preaching. And therefore the room for inculpable ignorance was reduced. A few priests wrote about this: once it has been said in public what is good and what is evil between spouses, ‘good faith can no longer be admitted.’
But decades of silence, interpreted by most of the faithful as consent to their contraceptive practice, had left its mark. In their answers to the question about birth control – a dozen years after ‘Casti Connubii’ – some priests recognized that their preaching on this matter made no impression: ‘We are in front of a wall that seems unassailable.’ And another wrote: ‘Even seemingly good persons cannot be persuaded.’
Read the whole article here.
A longer, academic article on this subject, by the author of the same book, is available here.