A:
Pope Pius IX proclaimed the doctrine of the Immaculate Conception in 1854. Strictly speaking, this was not an infallible doctrine, as the First Vatican Council had not yet approved the doctrine of papal infallibility. However, in 1870 the Vatican Council voted almost unanimously for the doctrine of papal infallibility, with only 2 opposed. One of Pius' opponents at the Council was subsequently excommunicated.
Catholic Answer:
The doctrine of the Immaculate Conception was defined and declared by Pope Pius IX on December 8, 1854.
In 1858, in an apparition the Church has approved as true and worthy of the belief and devotion of Catholics, the Blessed Virgin appeared to St. Bernadette Soubirou and called herself, "The Immaculate Conception", thereby identifying herself by the doctrine of the same name that had been declared in 1854.
Ex cathedra statements are rare declarations made by the Pope on matters of faith and morals that are considered infallible. One famous example is the doctrine of the Immaculate Conception, declared by Pope Pius IX in 1854. Another example is the doctrine of the Assumption of Mary, declared by Pope Pius XII in 1950. These statements are considered binding for all Catholics.
Pope Pius IX declared the Immaculate Conception of Mary an article of faith on the day of December 8, 1854. According to his pronouncement in Ineffabilis Deus, Mary was given grace to be sinless at the instant of her conception.
When the pope speaks ex cathedra (from the chair) on matters of faith and morals his words are without error and become part of Catholic doctrine. Except for declaring saints, the infallibility issue has only been used twice - when the pope declared the doctrine of the Immaculate Conception of Mary and when he declared the Assumption of Mary. It is only used after the subject has been studied for many years and only after consultation with all the bishops.
The Immaculate Conception
In 1854 Pope Pius IX declared that Mary was conceived without original sin (Immaculate Conception). This was interpreted to be that she never sinned throughout her life.
The dogma of the Immaculate Conception was officially proclained in 1854 by Pope Pius IX. It affirmed that the Blessed Virgin was born without the stain of Original Sin.
The cast of An Immaculate Conception - 2012 includes: Grace Aldrich as Grace Bridget Barkan as Bridget Tyler Pope as Tyler Elise Voigt as Elise
The doctrine of the Immaculate Conception, which states that Mary was conceived without original sin, has roots in early Christian tradition but was formally defined by the Catholic Church in 1854. Pope Pius IX proclaimed it as a dogma in the encyclical "Ineffabilis Deus." The belief had been developing since the Middle Ages, with various theologians advocating for it even earlier.
The pope is only infallible when speaking ex cathedra(from the chair) and only in matters of faith and morals and only after years of study and consultation with all the bishops. It has only been invoked twice in recent centuries - the doctrine of the Assumption of Mary and the doctrine of the Immaculate Conception of Mary. However, when a pope declares a person to be a saint it is also considered infallible.
The patroness of the United States is Our Lady of the Immaculate Conception. The National Shrine dedicated to Our Lady under this title is the Basilica of the National Shrine of the Immaculate Conception in Washington, D.C. This beautiful basilica is situated on the edge of the campus of the Catholic University of America and has been visited by both Pope John Paul II and Pope Benedict XVI on their visits to the city. The Feast of the Immaculate Conception is December 8.
Roman Catholic AnswerMary, herself, announced that she was the Immaculate Conception at her appearance in Lourdes, France in 1858. The Church's definition of the Immaculate Conception was made in 1854 by Pope Pius IX (Pio Nono) who defined it a dogma of the faith that must be believed, that Mary was conceived without stain of original sin due to the fact that she would bear the Son of God later in her life.