Are Ecclesiastical Disciplines Infallible?

Another Catholic wrote...

"People are confused about the limits of the Church's infallibility. It is really simple: They are only infallible in matters of faith and morals. NOT DISIPLINE."

On the contrary, Catholic theology teaches that ecclesiastical disciplines of the Church ARE infallible, but in an negative and indirect manner. Observe...

The Church has condemned the proposition that the Church can establish an ecclesiastical discipline that is "useless ... burdensome ... harmful ... dangerous."

Furthermore, according to the 1909 Catholic Encyclopedia article CATHOLIC ENCYCLOPEDIA: Ecclesiastical Discipline, the author calls the thesis that ecclesiastical disciplines are "indirectly infallible" as being held "unanimously" by Catholic theologians, and, rightly understood, is "undeniable." This was the traditional Catholic view under papacy of St. Pius X.

In the 18th century, Pius VI’s condemnation reads as follows:

The prescription of the synod [of Pistoia] ... it adds, "in this itself (discipline) there is to be distinguished what is necessary or useful to retain the faithful in spirit, from that which is useless or too burdensome for the liberty of the sons of the new Covenant to endure, but more so, from that which is dangerous or harmful, namely, leading to superstituion and materialism"; in so far as by the generality of the words it includes and submits to a prescribed examination even the discipline established and approved by the Church, as if the Church which is ruled by the Spirit of God could have established discipline which is not only useless and burdensome for Christian liberty to endure, but which is even dangerous and harmful and leading to superstition and materialism,--false, rash, scandalous, dangerous, offensive to pious ears, injurious to the Church and to the Spirit of God by whom it is guided, at least erroneous.

(Pius VI, Auctorem fidei, 78, cited in Denzinger, The Sources of Catholic Dogma, translated by Roy F. Deferari from the 13th ed. Of Henry Denzinger’s Enchiridion Symbolorum, 1954, Loreto Publications, 2nd printing, 2004, pg. 393)]

Similarly, Pope Gregory XVI wrote:

“…[they] state categorically that there are many things in the discipline of the Church ... [which] are harmful for the growth and prosperity of the Catholic religion.... While these men were shamefully straying in their thoughts, they proposed to fall upon the errors condemned by the Church in proposition 78 of the constitution Auctorem fidei (published by Our predecessor, Pius VI on August 28, 1794). ... do they not try to make the Church human by taking away from the infallible and divine authority, by which divine will it is governed? And does it not produce the same effect to think that the present discipline of the Church rests on failures, obscurities, and other inconveniences of this kind? And to feign that this discipline contains many things which are not useless but which are against the safety of the Catholic religion? Why is it that private individuals appropriate for themselves the right which is proper only for the pope (Encyclical Quo Graviora, October 4, 1833).

The Council of Trent declared:

“If anyone says that the ceremonies, vestments and outward signs, which the Catholic Church uses in the celebration of Masses, are incentives to impiety rather than the services of piety: let him be anathema.” (Session XXII, canon 7, Denz. 954.).

Furthermore, Pope Pius IX wrote:

“It would beyond any doubt be blameworthy and entirely contrary to the respect with which the laws of the Church should be received by a senseless aberration to find fault with the discipline which she has established, and which includes the administration of holy things, the regulation of morals, and the laws of the Church and her ministers; or to speak of this discipline as opposed to certain principles of the natural law, or to present it as defective, imperfect, and subject to civil authority.” (Mirari Vos, August 15, 1832.)

Pope Pius XII, Mystici Corporis, 66 (1943):“

"Certainly the loving Mother is spotless in the Sacraments, by which she gives inviolate; in her sacred laws imposed on all; in the evangelical counsels which she recommends; in those heavenly gifts and extraordinary graces through which, with inexhaustible fecundity, she generates hosts of martyrs, virgins and confessors.”

Also, according to P. Hermann, Institutiones Theologiae Dogmaticae (4th ed., Rome: Della Pace, 1908), vol. 1, p. 258:

“The Church is infallible in her general discipline. By the term general discipline is understood the laws and practices which belong to the external ordering of the whole Church. Such things would be those which concern either external worship, such as liturgy and rubrics, or the administration of the sacraments. . . .“If she [the Church] were able to prescribe or command or tolerate in her discipline something against faith and morals, or something which tended to the detriment of the Church or to the harm of the faithful, she would turn away from her divine mission, which would be impossible.”

I also refer you to the 1909 Catholic Encyclopedia article mentioned above, under the heading "DISCIPLINARY INFALLIBILITY".

Here's an excerpt...

[Disciplinary Infallibility] has, however, found a place in all recent treatises on the Church (De Ecclesiâ}. The authors of these treatises decide unanimously in favour of a negative and indirect rather than a positive and direct infallibility, inasmuch as in her general discipline, i. e. the common laws imposed on all the faithful, the Church can prescribe nothing that would be contrary to the natural or the Divine law, nor prohibit anything that the natural or the Divine law would exact. If well understood this thesis is undeniable; it amounts to saying that the Church does not and cannot impose practical directions contradictory of her own teaching.