3 The "Associations Cultuelles" did not come into existence, and therefore several persons - We use the words of Our Predecessor - thought it opportune to try, if possible, to create in their place another type of organization which would conform at one and the same time with the laws of France and the canons of the Church, and which would, considering the sad times which seemed to loom up in the near distance, be able to preserve intact, at least in substance, the sacrosanct rights of Holy Church. But as such a result seemed impossible of achievement at that time, Pope Pius, after consultation with the bishops of France, forbade any attempt to form this new type of Association, at least as long as the law of separation remained on the statute books, and until it could be established legally and beyond all doubt that in these same Associations the divine constitution of the Church, the inalienable rights of the Roman Pontiff and of the hierarchy, as well as the Church's authority over her property and, particularly over church buildings, would be both respected and safeguarded.
Source: Maximam Gravissimamque (Vatican.va)