A few days ago, someone asked me what Pius XII did to the rite of episcopal consecration after his encyclical Sacramentum Ordinis. Unlike his tinkering with the kalendar or hatchet job on Holy Week, his modifications to the Pontificale Romanum were relatively modest, if unfortunate. In the Acta Apostolicae Sedes for 1950, one can find a decree from Cardinal Micara "mandating the following changes and additions to the rubrics of the Roman Pontifical" to conform with the Pope's letter which "determined the form of the Sacrament of Orders" for Deacon, Priest, and Bishop.
The changes were modest, but did reflect the increasing shift towards receiving liturgy from Papal commissions who ensured the rites of the Church reflected the Pope's theology rather than the older paradigm.
Previously, an episcopal consecration employed one consecrating bishop, who would, with two other co-consecrators, lay hands on the episcopal candidate(s), but would say the prayers of the rite alone. Much like concelebration in the Byzantine rite, co-consecration of a bishop was meant as an act of brotherhood in which each participant did his own part. In the Greek rite, the concelebrants can sing litanies, distribute Communion, participate in the incensations and the like, but only the bishop says the anaphora. Similarly, the consecrating bishop carried out the elevation of the candidate and the other bishops attended as a fraternal sign; psalm 134 Ecce quam bonum was sung during the rite. after all. They laid their hands on the one who would join them among the successors to the Apostles, who Scripture called the "brethren" many times, but that was the extent of their place. In the revised form the co-consecrators carry out all the essentials of the rite along with the [now primary] consecrating bishop.
The revised rite calls for all consecrators to lay their hands on the candidates, say the words Accipe Spiritum Sanctum with the intention of consecration, and to say the preface which includes the words Pius XII decided constituted the absolutely essential form "Complete/perfect in Your priest the fullness of Your ministry and sanctify him with celestial anointing, clothing him with the ornaments of spiritual glorification." In the Roman tradition, anything about to become consecrated or sanctified in a special way is blessed with a preface: the palms on Palm Sunday, the Eucharist (prior to the silent Canon), priestly ordination, the Baptismal font, the Paschal candle, and churches when consecrated. Sadly, this changed people's association of the preface with sanctification and the "form" became the focus as though it is a stand alone prayer.
Here is a picture of William Cardinal Godfrey's Pontificale Romanum, now owned by the esteemed Mr. Rubricarius, revised according to the Pian changes.
The chanted form was suppressed in favor of recitation by all three bishops
Again, the alterations were not drastic, but they do reflect the imbalance of liturgy and theology that came to a head during the 20th century, the centralization, and the gearing up towards a reform. I wonder, would Paul VI have been able to change the rites had his mentor not limited the essential forms to one line?
"Among the other documents of the supreme Magisterium dealing with sacred Orders, We judge worthy of special mention the Apostolic Constitution Sacramentum Ordinis, published by Our predecessor Pius XII on November 30, 1947, in which it is declared that "the matter, and the only matter, of the Sacred Orders of the Diaconate, the Priesthood, and the Episcopacy is the imposition of hands; and that the form, and the only form, is the words which determine the application of this matter, which univocally signify the sacramental effects—namely, the power of Order and the grace of the Holy Spirit—and which are accepted and used by the Church in that sense." (9) After this the same document decrees what imposition of hands and what words constitute the matter and the form in the conferring of each Order.
"Since in the revision of the rite it was necessary either to add, delete or change certain things whether to restore to the texts greater fidelity to the ancient texts or to express better the effects of the sacrament, We have deemed it necessary, both to clear up all controversy and to obviate anxiety of conscience, to declare what things in the revised rite are to be said to pertain to the essence of the rite. Hence, in virtue of Our supreme Apostolic authority, We decree and determine the following, with regard to the matter and the form in the conferring of each sacrament....." Pope Paul VI, November 18th, 1968 in Pontificalis Romani
If anyone wants to read the old consecration rite in English, they can find it here. Interestingly, the translator puts a note within a note (not found in the Pontifical), correcting the notion that the laying of hands "was the essential rite" by citing Sacramentum Ordinis's teaching that the laying of hands is essential matter and the last words of the preface-turned-said prayer are the essential form.
Does it matter? I doubt anyone has used the pre-Pius XII rite of consecration since 1950. The last [canonical] consecration in the old rite was that of Bishop Rifan in Campos by Cardinal Hoyos. Before that was, of course, Archbishop Lefebvre at Econe. Both would have been done according to 1962. The sedevacantist bishops tend to follow Pius XII until he touched Holy Week. Daniel Dolan received his orders from bishop Mark Pivarunas of Pius XII-devout CMRI. Unlike Holy Week or the Office, this is a minor subject in my book and I doubt we will be revisiting it.
Spoken preface/essential form at 11:50