Was Vatican I An Ecumenical Council?

If Vatican I was not an "ecumenical council," then its definitions are not binding on anyone.  Our previous post included an article that detailed the history of the council.  The attentive reader would have noticed that at the time of the council there were complaints regarding the lack of freedom enjoyed by that fathers at the council.  A council that is not truly free is not truly a council.

Aside from the question of liberty, or lack there of, at the council we have to ask what the definition of an ecumenical council is? 

The clearest description of the conditions necessary for a council to be regarded as ecumenical was given by the seventh Ecumenical Council (Nicaea II, 787), the final council to be recognised as ecumenical both in the East and in the West:

– it has to be accepted by the heads (proedroi) of the churches, and they have to be in agreement (symphonia) with it;

– the pope of Rome has to be a “co-operator” or “fellow worker” (synergos) with the council;

– the patriarchs of the East have to be “in agreement” (symphronountes);

– the teaching of the council must be in accord with that of previous ecumenical councils;

– the council must be given its own specific number, so as to be placed in the sequence of councils accepted by the Church as a whole.

I understand most Catholics have a different definition today of what an ecumenical is, but this blog is dedicated to the ancient catholic understanding because we believe that a catholic should follow the canon of St. Vincent in determining catholic orthodoxy.
It is also noteworthy that modern scholarship is slowly returning to this principal.  To wit the Joint International Commission For The Theological Dialogue Between The Roman Catholic Church and the Orthodox Church agree that the holding of truly ecumenical council was rendered impossible after the schism between the two churches.

39. Unlike diocesan and regional synods, an Ecumenical Council is not an “institution” whose frequency can be regulated by canons; it is rather an “event”, a kairos inspired by the Holy Spirit who guides the Church so as to engender within it the institutions which it needs and which respond to its nature. This harmony between the Church and the councils is so profound that, even after the break between East and West which rendered impossible the holding of Ecumenical Councils in the strict sense of the term, both Churches continued to hold councils whenever serious crises arose. These councils gathered together the bishops of local Churches in communion with the See of Rome or, although understood in a different way, with the See of Constantinople, respectively. In the Roman Catholic Church, some of these councils held in the West were regarded as ecumenical. This situation, which obliged both sides of Christendom to convoke councils proper to each of them, favoured dissensions which contributed to mutual estrangement. The means which will allow the re-establishment of ecumenical consensus must be sought out.
For more please see  The Revenna Documents