This Mémoire Préliminaire de Thèse (MPT) is presented in support of the Ph.D. thesis 'Fault as a Basis for Liability in Investment Treaty Arbitration', undertaken at the Department of International Law at the Graduate Institute Geneva, to be assessed by the thesis supervisor (Prof. Zachary Douglas) and second reader (Prof. Joost Pauwelyn). It is composed of two parts: the thesis outline (Part One) and the draft of the thesis' first chapter (Part Two).., undertaken at the Department of International Law at the Graduate Institute Geneva., to be assessed by the thesis supervisor (Prof. Zachary Douglas) and second reader (Prof. Joost Pauwelyn). It is composed of two parts: the thesis outline (Part One) and the draft of the thesis' first chapter (Part Two).