3 But whereas other Governments in recent times have been eager to renew agreements with the Holy See, that of Mexico frustrated every attempt to arrive at an understanding. On the contrary, it most unexpectedly broke the promises made to Us shortly before in writing, banishing repeatedly Our Representatives and showing thereby its animosity against the Church. Thus a most rigorous application was given to Article 130 of the Constitution, against which, on account of its extreme hostility to the Church, as may be seen from Our Encyclical Iniquis afflictisque of November 18, 1926, the Holy See had to protest in the most solemn manner. Heavy penalties were then enacted against the transgressors of this deplorable article; and, as a fresh affront to the Hierarchy of the Church, it was provided that every State of the Confederation should determine the number of priests empowered to exercise the sacred ministry, in public or in private.
Source: Acerba Animi (Vatican.va)