The purpose of this thesis is to explore the nature of arbitration, the powers and duties of arbitrators and finally the relationships between national courts and arbitration in the light of English, French and Scottish legal systems as well as the ICC Rules. These three ideas will be examined in accordance with the three legal systems and the ICC Rules in three consecutive parts. In the first part, the nature of arbitration will be investigated in the light of certain methods of alternative dispute resolution (ADR) namely mediation and conciliation and compared with expertise and valuation. The purpose is to identify the nature of arbitration and this justifies the comparison with these similar concepts. This will lead to the formulation of the writer's personal definition of arbitration. In the second chapter of this first part, the definitions of the term 'arbitration', if any, will be considered for each legal system and the ICC Rules. The first part plays the role of an introductory part with a view to assisting the understanding of the reader before entering into the heart of the matter. In the second part, the powers and duties of arbitrators will be considered. Powers are granted to arbitrators by the parties in the arbitration agreement, failing which legislation will confer certain powers on arbitrators to ensure that they can conduct arbitration in the best way possible. Procedural powers, powers of investigation, powers as to hearing, powers which ensure the good functioning of the arbitration and so on will be studied according to the legal texts and rules under study. A total of 18 powers are studied. The corollary of this is that arbitrators have to comply with some mandatory rules either imposed by legislation and international rules or by the parties to arbitration : they are described in the following chapter. Ethical duties related to independence, impartiality, neutrality, confidentiality: duties as to the procedure; duties as to the award and several others are considered: a total of 22 duties are studied according to the texts under study. The third part is concerned with the relationships between national courts and arbitration.