Evidence in International Investment Arbitration is a guide for practitioners representing a party in investment arbitration disputes, whilst also offering academics a perspective on the practical elements affecting the treatment of evidence in the area. The book is the first of its kind to systematically review the jurisprudence of investor-state tribunals on evidentiary matters and inductively establish the rules recognized in those decisions. It uses a comparative approach to demonstrate the points of commonality and uniformity in the transnational foundations of the law of evidence as it affects international investment arbitration, providing theoretical and practical guidance on the treatment of evidence at all stages of such disputes. The work establishes the rules of evidence as currently recognized by investor-state arbitral jurisprudence and examines these rules of evidence against those recognized in the traditional rules of international law, as well as against those codified by the IBA Rules on the Taking of Evidence in International Arbitration. It examines the theory and function of international investment law dispute resolution against which the role of evidence must be assessed; practical management of the evidence-gathering process in investment arbitration disputes; and what to anticipate as challenges in the gathering and pleading of evidence in these disputes. Chapters cover a broad range of evidence-based topics, including: burden and standard of proof, presumptions and inferences, witness and expert evidence, exclusionary rules including privileged and confidential documents, and annulment. Written by a small team of practitioners and academics who are expert in the field of international dispute resolution, this book is an essential comprehensive reference work for anyone working or studying in the field.