In such case, before going further, the Council must call upon the parties to submit their dispute to judicial settlement or to arbitration. It is only in the case where this appeal--which the Council will make in the manner which appears to it most likely to secure a favourable hearing--is not listened to that the procedure will acquire the compulsory character which is necessary to make certain the final settlement of all disputes. There are three alternatives: (_a_) Compulsory arbitration at the request of one of the parties; (_b_) A unanimous decision by the Council; (_c_) Compulsory arbitration enjoined by the Council. Appropriate methods are laid down for all three cases. _Article 4, paragraph 2._ _First case of Compulsory Arbitration_.--If the parties, being called upon by the Council to submit their dispute to a judicial or arbitral settlement, do not succeed in coming to an agreement on the subject, there is no question of optional arbitration, but if a single party desires arbitration, arbitration immediately becomes compulsory. The dispute is then _ipso facto_ referred to a Committee of Arbitrators, which must be constituted within such time limit as the Council shall fix. {176} Full liberty is left to the parties themselves to constitute this Committee of Arbitrators. They may agree between themselves in regard to the number, names and powers of the arbitrators and the procedure. It is to be understood that the word "powers" is to be taken in the widest sense, including, _inter alia_, the questions to be put. It was not considered desirable to develop this idea further. It appeared to be sufficient to state that any result which could be obtained by means of an agreement between the parties was preferable to any other solution. It also appeared inexpedient to define precisely the powers which should be conferred upon the arbitrators. This is a matter which depends upon the circumstances of each particular case. According to the case, the arbitrators, as is said above, may fill the rôle of judges giving decisions of pure law or may have the function of arranging an amicable settlement with power to take account of considerations of equity. It has not been thought necessary to lay this down in the form of a rule. It has appeared preferable to leave it in each case to the parties to agree between themselves to decide the matter according to the circumstances of the case.