Here is some material by Michael Davies on the subject of schism in
general and Archishop Lefebvre in particular.  He wrote it around
1990.  The first part of the two-part article was on the scandalous
activities of Archbishop Weakland (in this country), but I cut all
that.  And I pared down the rest to what was relevant.

Joe Buehler

...

Schism and Disobedience

According to St. Thomas Aquinas, schism consists primarily in a
refusal of submission to the Pope or communion with the members of the
Church united to him. On first sight it would appear that, whatever
the subjective motivation of the Archbishop, as discussed above, he
must be in a state of objective schism as he has refused to submit to
the Pope on a very grave matter involving his supreme power of
jurisdiction. However, standard Catholic textbooks of theology make it
clear that while all schisms involve disobedience not all acts of
disobedience are schismatic. If this were so, as was noted at the
beginning of this article, it would mean that the number of American
bishops who are not schismatic would not reach double figures.

The distinction between disobedience and schism is made very clear in
the article on schism in the very authoritative Dictionnaire de
Theologie Catholique. The article is by Father Yves Congar who is
certainly no friend of Archbishop Lefebvre.  He explains that schism
and disobedience are so similar that they are often confused. Father
Congar writes that schism involves a refusal to accept the existence
of legitimate authority in the Church, for example, Luther's rejection
of the papacy. Father Congar explains that the refusal to accept a
decision of legitimate authority in a particular instance does not
constitute schism but disobedience.  The Catholic Encyclopedia
explains that for a Catholic to be truly schismatic he would have to
intend "to sever himself from the Church as far as in him lies."  It
adds that "not every disobedience is schism; in order to possess this
character it must include besides the transgression of the command of
the superiors, a denial of their divine right to command."Not only
does Mgr. Lefebvre not deny the divine right of the Pope to command,
but he affirms repeatedly his recognition of the Pope's authority and
his intention of never breaking away from Rome. The Archbishop made
his attitude clear in the July/August 1989 issue of 30 Days: "We pray
for the Pope every day. Nothing has changed with the consecrations
last June 30. We are not sedevacantists. We recognize in John Paul II
the legitimate Pope of the Catholic Church. We don't even say that he
is a heretical Pope. We only say that his Modernist actions favor
heresy."

...

Intrinsically Schismatic?

The principal argument used by those claiming that Mgr. Lefebvre is in
schism is that the consecration of a bishop without a papal mandate is
an intrinsically schismatic act. A bishop who carries out such a
consecration, it is claimed, becomes ipso facto a schismatic. This is
not true. If such a consecration is an intrinsically schismatic act it
would always have involved the penalty of excommunication. In the 1917
Code of Canon Law the offence was punished only by suspension (see
Canon 2370 of the 1917 Code). Pope Pius XII had raised the penalty to
excommunication as a response to the establishment of a schismatic
church in China. The consecration of these illicit Chinese bishops
differed radically from the consecrations carried out by Mgr. Lefebvre
as the professed intention was to repudiate the authority of the Pope,
that is, to deny that he has the right to govern the Church, and the
illicitly consecrated Chinese bishops were given a mandate to exercise
an apostolic mission. Neither Archbishop Lefebvre nor any of the
bishops he has consecrated claim that they have powers of
jurisdiction. They have been consecrated solely for the purpose of
ensuring the survival of the Society by carrying out ordinations and
also to perform confirmations. I do not wish to minimize in any way
the gravity of the step take by Mgr. Lefebvre. The consecration of
bishops without a papal mandate is far more serious matter than the
ordination of priests as it involves a refusal in practice of the
primacy or jurisdiction belonging by divine right to the Roman
Pontiff. But the Archbishop could argue that the crisis afflicting the
Church could not be more grave, and that grave measures were needed in
response.

It appears to be taken for granted by most of the Archbishop's critics
that he was excommunicated for the offense of schism, and the Vatican
has certainly been guilty of fostering this impression.  There is not
so much as a modicum of truth in this allegation. The New Code of
Canon Law includes a section beginning with Canon 1364 entitled
"Penalties for Specific Offenses" (De Poenis in Singula Dicta). The
first part deals with "Offenses against Religion and the Unity of the
Church" (De Delictis contra Religionem et Ecclesiae Unitatem). Canon
1364 deals with the offense of schism which is, evidently, together
with apostasy and heresy, one of the three fundamental offenses
against the unity of the Church.

But the Archbishop was not excommunicated under the terms of this
canon or, indeed, under any canon involving an offense against
religion or the unity of the church. The canon cited in his
excommunication comes from the third section of "Penalties for
Specific Offenses" which is entitled "Usurpation of Ecclesial
Functions and Offenses in their Exercise" (De Munerum Ecclesiasticorum
Usurpatione Degue Delictis iniis Exercendis). The canon in question is
Canon 1382, which reads: "A bishop who consecrates someone bishop and
the person who receives such a consecration from a bishop without a
pontifical mandate incur an automatic (latae sententiae)
excommunication reserved to the Holy See."

The scandalous attempts to smear Archbishop Lefebvre with the offense
of schism are, then, contrary to both truth and charity. A comparable
smear under civil as opposed to ecclesiastical law would certainly
justify legal action for libel involving massive damages. An accurate
parallel would be to state that a man convicted of manslaughter had
been convicted of first degree murder.

I must stress that what I have written here is not the dubious opinion
of laymen unversed in the intricacies of Canon Law. Canon lawyers
without the least shred of sympathy for Mgr. Lefebvre have repudiated
the charge of schism made against him as totally untenable. Father
Patrick Yaldrini, Dean of the Faculty of Canon Law of the Institut
Catholique in Paris noted in the 4 July 1988 issue of Valeurs
actuelles that, as I have just explained, Mgr.  Lefebvre was not
excommunicated for schism but for the usurpation of an ecclesiastical
function. He added that it is not the consecration of a bishop which
constitutes schism but the conferral of an apostolic mission upon the
illicitly consecrated bishop. It is this usurpation of the powers of
the sovereign pontiff which proves the intention of establishing a
parallel Church.

Cardinal Rosalio Lara, President of the Pontifical Commission for the
Authentic Interpretation of Canon Law, commented on the consecrations
in the 10 July 1988 issue of la Repubblica. It would be hard to

    The act of consecrating a bishop (without a papal mandate) is not
    in itself a schismatic act. In fact, the Code that deals with
    offenses is divided into two sections. One deals with offenses
    against religion and the unity of the Church, and these are
    apostasy, schism, and heresy. Consecrating a bishop with a
    pontifical mandate is, on the contrary, an offense against the
    exercise of a specific ministry. For example, in the case of the
    consecrations carried out by the Vietnamese Archbishop Ngo Dinh
    Thuc in 1976 and 1983, although the Archbishop was excommunicated
    he was not considered to have committed a schismatic act because
    there was no intention of a breach with the Church.

....

It is not simply unjust but ludicrous to suggest that in consecrating
bishops without a papal mandate Archbishop Lefebvre had the least
intent of establishing a schismatic church. He is not a schismatic and
will never be a schismatic. The Archbishop considers correctly that
the the Church is undergoing its worst crisis since the Arian heresy,
and that for the good of the Church it was necessary for him to
consecrate the four bishops to ensure the future of his Society. Canon
Law provides for just such a situation, and even if one believes that
the future of the Society could have been guaranteed without these
consecrations, the fact that the Archbishop believed sincerely that it
could not means, as Canon Law states clearly, that he has not incurred
excommunication. Furthermore, while the Vatican allows such prelates
as Archbishop Weakland to undermine the Faith with impunity it cannot
expect Catholics to pay the least attention to its sanctions against a
great and orthodox Archbishop whose entire life has been devoted to
the service of the Church and the salvation of souls.

Dr. Eric M. de Saventhem, President of the International Una Voce
Association, is one of the best informed laymen in the Church, and he
knows the Archbishop intimately. Dr. de Saventhem, like myself, has no
greater desire than to see a reconciliation between Mgr. Lefebvre and
the Holy See during the Archbishop's lifetime. A quotation from a
statement by Dr. de Saventhem which was published in the 15 February
1989 Remnant merits careful study: