The dichotomy between jurisdiction and admissibility developed in public international law has drawn much attention from arbitrators and judges in recent years. Inspired by Paulsson's ‘tribunal versus claim’ lodestar, attempts have been made to transpose the distinction from public international law to investment treaty arbitration, yielding a mixed reception from tribunals. Remarkably, a second leap of transposition has found firmer footing in commercial arbitration, culminating in the prevailing view of the common law courts in England, Singapore and Hong Kong that arbitral decisions on admissibility are non-reviewable. However, this double transposition from international law to commercial arbitration is misguided. First, admissibility is a concept peculiar to international law and not embodied in domestic arbitral statutes. Second, its importation into commercial arbitration risks undermining the fundamental notion of jurisdiction grounded upon the consent of parties. Third, the duality of ‘night and day’ postulated by Paulsson to distinguish between reviewable and non-reviewable arbitral rulings is best reserved to represent the basic dichotomy between jurisdiction and merits.

This article explores the conditions under which it is possible to bring claims based on non-international investment agreement (IIA) norms of international law in investment treaty arbitration. For that purpose, it analyzes in the first instance broad dispute settlement clauses incorporated in IIAs that make reference to the settlement of ‘any investment dispute’. Such clauses grant jurisdiction to investment treaty tribunals to hear non-IIA claims. However, at least two additional conditions need to be satisfied for the investor to bring a self-standing claim based on a non-IIA norm of international law. First, the non-IIA instrument (a contract or another international treaty) may include a dispute settlement clause envisaging exclusive jurisdiction in favour of another forum. Second, the investor's standing to bring a claim based on a non-IIA norm of international law depends on whether this norm attributes any legal entitlement in the benefit of the investor.

The UNIDROIT Principles of International Commercial Contracts have appeared in a small but steady trickle of investment treaty arbitrations over the last decade. This article considers the use of the Principles by investment tribunals on questions of both domestic law and international law. It suggests that reference to the Principles can play an important legitimating role on questions of domestic law, but that this should not replace reference to the applicable law. On questions of international law, reference to the Principles may be justified by resort to the general principles of law. However, the article contends that there is only a limited role for the UNIDROIT Principles where the primary and secondary rules of investment protection are already found in treaties and custom. In addition, while general principles have historically been drawn from domestic private law, there is increasing recognition that general principles of public law are more relevant to investment arbitration. Given this, arbitrators resolving questions of international law must be cautious in references to the UNIDROIT Principles, a quintessentially private law instrument.

This paper critically discusses the issue of enforceability of investment treaty arbitration (ITA) awards against India under the Indian domestic law on arbitration. In this regard, the paper discusses the relevant provisions of the Indian arbitration law and its interpretations by the Indian judiciary to understand their ramifications for the enforcement of ITA awards against India. The paper also discusses the proposed amendments to the Indian arbitration law and its ramifications on ITA. The issue of enforcement of ITA awards in India has become important due to India's gigantic international investment treaty programme where each treaty allows for investor-state treaty arbitration to settle disputes between investors and India. This issue has also become important in light of the growing observation that enforcement of foreign commercial arbitral awards in India is extremely difficult especially after the Venture Global engineering case. Thus, India is endeavouring to change the arbitration law so as to alter this perception. This paper argues that in spite of these proposed changes; enforcement of ITA awards may still face problems. Thus, the paper suggests that India should address the issue of enforceability of ITA awards given its gigantic investment treaty programme aimed at attracting foreign investment.

The idea of investment treaty arbitration as public law is in tension with the concept of international law as a law between representative public agencies. This concept of international law is valuable for its capacity to progress a broad range of public policy aims in an integrated and coordinated manner, including aims extending beyond the economic sphere such as international social, environmental, cultural and related aims. The probable effect on this concept of international law of a radical ‘internationalized public law’ approach to investment treaty arbitration requires further thought, especially with regard to the potential implications of recognizing investor rights under international law.

Investment treaty arbitration, unlike commercial arbitration, is not a purely private dispute settlement mechanism that is entirely subject to party autonomy and limited in its effects to the parties to the proceedings. Rather, it fulfils a public function in influencing the behaviour of foreign investors, states, and civil society more generally by crafting and concretizing international standards of investment protection. Investment treaty arbitration thus implements and operates as part of a public system of investment protection. Arbitrators, as a result, incur obligations not only towards the parties to the proceedings, but vis-à-vis the whole system of investment protection. These obligations can be conceptualized as part of the public law implications of investment treaty arbitration and affect, inter alia, the role and status of arbitrators in investment treaty disputes, the procedural maxims that such arbitrations should follow, and the way arbitral awards should be crafted.