"The Vatican said Tuesday that countries which decided to wage war on Iraq without the consensus of the international community were assuming great responsibility before God and history."
And here a Bishop says:
"Bishop Botean acknowledged that the Catechism of the Catholic Church (2309) identifies public authorities as the final judges of whether military action is justified. But he argued that "the nation-state is never the final arbiter or authority for the Catholic of what is moral." An unjust law or order should not be obeyed, he observed."
Which Catholic authority is correct?
Sources of infallible doctrine within the Church are the teachings of the Church, meeting in Council, and the teachings of the Pope from the Chair of Peter.
Otherwise, bishops must obey the pope's disciplinary teachings within reason.
The definition of infallibility according to the Catholic Encyclopedia.
Here's the scope of infallibility, in particular:
V. WHAT TEACHING IS INFALLIBLE?A word or two under this head, summarizing what has been already explained in this and in other articles will suffice.
As regards matter, only doctrines of faith and morals, and facts so intimately connected with these as to require infallible determination, fall under tbe scope of infallible ecclesiastical teaching. These doctrines or facts need not necessarily be revealed; it is enough if the revealed deposit cannot be adequately and effectively guarded and explained, unless they are infallibly determined.
As to the organ of authority by which such doctrines or facts are determined, three possible organs exist. One of these, the magisterium ordinarium, is liable to be somewhat indefinite in its pronouncements and, as a consequence, practically ineffective as an organ. The other two, however, are adequately efficient organs, and when they definitively decide any question of faith or morals that may arise, no believer who pays due attention to Christ's promises can consistently refuse to assent with absolute and irrevocable certainty to their teaching.
But before being bound to give such an assent, the believer has a right to be certain that the teaching in question is definitive (since only definitive teaching is infallible); and the means by which the definitive intention, whether of a council or of the pope, may be recognized have been stated above. It need only be added here that not everything in a conciliar or papal pronouncement, in which some doctrine is defined, is to be treated as definitive and infallible. For example, in the lengthy Bull of Pius IX defining the Immaculate Conception the strictly definitive and infallible portion is comprised in a sentence or two; and the same is true in many cases in regard to conciliar decisions. The merely argumentative and justificatory statements embodied in definitive judgments, however true and authoritative they may be, are not covered by the guarantee of infallibility which attaches to the strictly definitive sentences -- unless, indeed, their infallibility has been previously or subsequently established by an independent decision.