There are two aspects to the problem: first, aggression has to be defined, and, secondly, its existence has to be ascertained.

The definition of aggression is a relatively easy matter, for it is sufficient to say that any State is the aggressor which resorts in any shape or form to force in violation of the engagements contracted by it either under the Covenant (if, for instance, being a Member of the League of Nations, it has not respected the territorial integrity or political independence of another Member of the League) or under the present Protocol (if, for instance, being a signatory of the Protocol, it has refused to conform to an arbitral award or to a unanimous decision of the Council). This is the effect of Article 10, which also adds that the violation of the rules laid down for a demilitarised zone is to be regarded as equivalent to resort to war. The text refers to resort to war, but it was understood during the discussion that, while mention was made of the most serious and striking instance, it was in accordance with the spirit of the Protocol that acts of violence and force, which possibly may not constitute an actual state of war, should nevertheless be taken into consideration by the Council.

On the contrary, to ascertain the existence of aggression is a very difficult matter, for although the first of the two elements which together constitute aggression, namely, the violation of an engagement, is easy to verify, the second, namely, resort to force, is not an easy matter to ascertain. When one country attacks another, the latter necessarily defends itself, and when hostilities are in progress on both sides, the question arises which party began them.

This is a question of fact concerning which opinions may differ.

The first idea which occurs to the mind is to make it the duty of the Council to determine who is the aggressor. But, immediately, the question arises whether the Council must decide this question unanimously, or whether a majority vote would suffice. There are serious disadvantages in both solutions and they are therefore unacceptable.

To insist upon a unanimous decision of the Council exposes the State attacked to the loss of those definite guarantees to which it is entitled, if one single Member of the Council—be it in good faith or otherwise—insists on adhering to an interpretation of the facts different from that of all his colleagues. It is impossible to admit that the very existence of a nation should be subject to such a hazard. It is not sufficient to point out that the Council would be bound to declare the existence of aggression in an obvious case and that it could not fail to carry out its duty. The duty would be a duty without a sanction and if by any chance the Council were not to do its duty, the State attacked would be deprived of all guarantees.

But it would also be dangerous to rely on a majority vote of the Council. In that case, the danger would be incurred by the State called upon to furnish assistance and to support the heavy burden of common action, if it still entertained some doubt as to the guilt of the country against which it had to take action. Such a country would run the risk of having to conform to a decision with which it did not agree.

The only escape from this dilemma appeared to lie in some automatic procedure which would not necessarily be based on a decision of the Council. After examining the difficulty and discussing it in all its aspects, the First Committee believes that it has found the solution in the idea of a presumption which shall hold good until the contrary has been established by a unanimous decision of the Council.

The Committee is of opinion that this presumption arises in three cases, namely, when a resort to war is accompanied:

By a refusal to accept the procedure of pacific settlement or to submit to the decision resulting therefrom;