The Roman Catholic Church has officially declared the filioque as true in multiple of their infallible councils and even in their old official catechism. This is an indisputable fact that I'm sure we would all agree on. Here are some examples of what these councils said:
The 4th Lateran Council, 1215
1. Confession of Faith
“The Father is from no one; the Son is from the Father only; and the Holy Spirit is from both the Father and the Son equally.”
The 2nd Council of Lyons, 1274
On the supreme Trinity and the catholic faith
“...We profess faithfully and devotedly that the holy Spirit proceeds eternally from the Father and the Son, not as from two principles, but as from one principle; not by two spirations, but by one single spiration...”
The Council of Florence, 1438-45
LAETENTUR CAELI
“declarantes quod id, quod sancti doctores et patres dicunt, ex Patre per Filium procedere Spiritum sanctum, ad hanc intelligentiam tendit, ut per hoc significetur Filium quoque esse, secundum Grecos quidem causam, secundum Latinos vero principium subsistentie Spiritus sancti, sicut et Patrem.”
“We declare that when holy doctors and fathers say that the Holy Spirit proceeds from the Father through the Son, this holds an understanding which signifies that the Son, like the Father, is according to the Greeks indeed 'cause' and according to the Latins 'principle' of the subsistence of the Holy Spirit, just as also the Father.”
The Catechism of the Council of Trent
(The offical Roman Catholic catechism until 1994)
“I.8.6. With regard to the words immediately succeeding: “who proceedeth from the Father and the Son,” the faithful are to be taught, that the Holy Ghost proceeds by eternal procession, from the Father and the Son, as from one principle : a truth propounded to us by an ecclesiastical rule, from which the least departure is unwarrantable.”
However, the current Roman Catholic Church says that the Holy Spirit does not eternally proceed from the Son equally but only from the Father through the Son with the Father as the sole cause. This view is especially upheld amongst the Eastern Catholics and is declared by the Pontifical Council for Promoting Christian Unity.
Explaining this, the Pontifical Council for Promoting Christian Unity says the following:
“The Father alone is the principle without principle (arch anarco) of the two other persons of the Trinity, the sole source (phgh) of the Son and of the Holy Spirit. The Holy Spirit therefore takes his origin from the Father alone (ek monou tou PatroV) in a principal, proper and immediate manner. The Greek Fathers and the whole Christian Orient speak, in this regard, of the "Father's monarchy", and the Western tradition, following St Augustine, also confesses that the Holy Spirit takes his origin from the Father "principaliter", that is, as principle (DeTrinitate XV, 25, 47, PL 42, 1094-1095). In this sense, therefore, the two traditions recognize that the "monarchy of the Father" implies that the Father is the sole Trinitarian Cause (Aitia) or principle (principium) of the Son and of the Holy Spirit...
The doctrine of the Filioque must be understood and presented by the Catholic Church in such a way that it cannot appear to contradict the Monarchy of the Father nor the fact that he is the sole origin (arch, aitia) of the ekporeusi of the Spirit.”
The current formulation of the Catholic Church affirms the monarchy of the Father and maintains that he is the sole origin of the Spirit. This, of course, contradicts previous teaching which had the Spirit proceeding from the Father and Son equally and both being causes of the Spirit.
Thus, we see that today they contradict a past infallible teaching.
"I wanted to copy and paste this in case the original author deletes his account"
The 4th Lateran Council, 1215
1. Confession of Faith
“The Father is from no one; the Son is from the Father only; and the Holy Spirit is from both the Father and the Son equally.”
The 2nd Council of Lyons, 1274
On the supreme Trinity and the catholic faith
“...We profess faithfully and devotedly that the holy Spirit proceeds eternally from the Father and the Son, not as from two principles, but as from one principle; not by two spirations, but by one single spiration...”
The Council of Florence, 1438-45
LAETENTUR CAELI
“declarantes quod id, quod sancti doctores et patres dicunt, ex Patre per Filium procedere Spiritum sanctum, ad hanc intelligentiam tendit, ut per hoc significetur Filium quoque esse, secundum Grecos quidem causam, secundum Latinos vero principium subsistentie Spiritus sancti, sicut et Patrem.”
“We declare that when holy doctors and fathers say that the Holy Spirit proceeds from the Father through the Son, this holds an understanding which signifies that the Son, like the Father, is according to the Greeks indeed 'cause' and according to the Latins 'principle' of the subsistence of the Holy Spirit, just as also the Father.”
The Catechism of the Council of Trent
(The offical Roman Catholic catechism until 1994)
“I.8.6. With regard to the words immediately succeeding: “who proceedeth from the Father and the Son,” the faithful are to be taught, that the Holy Ghost proceeds by eternal procession, from the Father and the Son, as from one principle : a truth propounded to us by an ecclesiastical rule, from which the least departure is unwarrantable.”
However, the current Roman Catholic Church says that the Holy Spirit does not eternally proceed from the Son equally but only from the Father through the Son with the Father as the sole cause. This view is especially upheld amongst the Eastern Catholics and is declared by the Pontifical Council for Promoting Christian Unity.
Explaining this, the Pontifical Council for Promoting Christian Unity says the following:
“The Father alone is the principle without principle (arch anarco) of the two other persons of the Trinity, the sole source (phgh) of the Son and of the Holy Spirit. The Holy Spirit therefore takes his origin from the Father alone (ek monou tou PatroV) in a principal, proper and immediate manner. The Greek Fathers and the whole Christian Orient speak, in this regard, of the "Father's monarchy", and the Western tradition, following St Augustine, also confesses that the Holy Spirit takes his origin from the Father "principaliter", that is, as principle (DeTrinitate XV, 25, 47, PL 42, 1094-1095). In this sense, therefore, the two traditions recognize that the "monarchy of the Father" implies that the Father is the sole Trinitarian Cause (Aitia) or principle (principium) of the Son and of the Holy Spirit...
The doctrine of the Filioque must be understood and presented by the Catholic Church in such a way that it cannot appear to contradict the Monarchy of the Father nor the fact that he is the sole origin (arch, aitia) of the ekporeusi of the Spirit.”
The current formulation of the Catholic Church affirms the monarchy of the Father and maintains that he is the sole origin of the Spirit. This, of course, contradicts previous teaching which had the Spirit proceeding from the Father and Son equally and both being causes of the Spirit.
Thus, we see that today they contradict a past infallible teaching.
"I wanted to copy and paste this in case the original author deletes his account"
“Roman Catholics, in the midst of a disintegrating church structure, are finding that Orthodoxy is everything they once thought Roman Catholicism to be." - Fr. Seraphim Rose