[The retired bishop of Fribourg] granted Lefebvre’s request and, with a document predated by six days to 1 November 1970, he established the Society of St. Pius X as a pia unio (Latin, for “pious, or holy, union”) on a provisional ( ad experimentum ) basis for six years. Pia unio status was the first stage through which a Catholic organisation passed prior to gaining official recognition as a religious institute or society of apostolic life…The Society of Saint Pius X was formally founded, adhering to all canonical norms, and receiving the episcopal blessing and encouragement of the local ordinary.
On 6 May 1975, with the approval of the cardinals, Bishop [of Fribourg] withdrew the SSPX’s pia unio status. Lefebvre instructed his lawyer to lodge appeals and he ultimately petitioned the Apostolic Signatura, the highest court of the Catholic Church, which turned down the complaint. From this point onwards, the SSPX was no longer recognised as a canonical organization.
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