General international law is part and parcel of investor-state arbitration. This is the case not only regarding treaty law and state responsibility, but also with respect to matters such as state succession, the international minimum standard, and state immunity, all of which feature regularly in investor-state arbitration. Yet, although general international law issues arise in almost every investment case and often require extensive research, no systematic exploration of the relationship between the two exists. This Commentary is the first to fill this gap, providing a comprehensive treatment of the role of general international law in international investment law. It engages in detail with central matters of general international law, including in the practice of investment arbitration tribunals, moving beyond existing works which focus solely on procedural and institutional provisions.

The Commentary's forty-six chapters do not focus on a single source or subject. Instead, each concentrates on a specific, relevant article from a particular source of public law - such as the Vienna Convention on the Law of Treaties (1969) or the International Law Commission's Articles on the Responsibility of States for Internationally Wrongful Acts (2001), among others. The entries combine detailed analysis with an examination of procedural and substantive aspects - such as nationality and unjust enrichment - and respond to the following questions: how have investment tribunals interpreted and applied the specific rule of general international law? To what extent and why does such interpretation and application align with or deviate from the practice by other international courts or tribunals? How could and should investment tribunals interpret and apply rules that have yet to feature in investment arbitration? This unique format means this commentary will serve as a central guide for all relevant case law and scholarship on international investment law.

Andreas Kulick, Senior Research Fellow, Eberhard Karls Universit"at T"ubingen, Michael Waibel, Professor of International Law, University of Vienna

Andreas Kulick is a senior research fellow at the Eberhard Karls Universit"at T"ubingen. He has been a visiting fellow at the Lauterpacht Centre for International Law, the European University Institute, NYU School of Law, and the WZB Berlin. His research focuses on public international law, particularly on international dispute settlement, international economic law, and general international law. He advises and represents states and other actors in various matters of public international law before international courts and tribunals.


Michael Waibel is a professor of international law at the University of Vienna. His teaching and writing focuses on international law, international economic law, sovereign debt, and international dispute settlement. He is Co-General Editor of the ICSID Reports and Co-Editor-in-Chief of the Journal of International Economic Law. He previously taught at the University of Cambridge and served as Co-Deputy Director of the Lauterpacht Centre.

PrefaceTable of ContentsList of ContributorsTable of CasesGeneral international law in international investment law, Andreas Kulick and Michael WaibelPART I: LAW OF TREATIES (VCLT)1. Article 18 of the VCLT: Obligation not to defeat the object and purpose of a treaty prior to its entry into force, Belinda McRae2. Articles 19-23 of the VCLT: Reservations (overview) - flexibility devices in applying treaties in the field of investment, Alain Pellet and Jean-Baptiste Merlin3. Article 24 of the VCLT: Entry into force, Tania Voon4. Article 25 of the VCLT: Provisional application, Tania Voon5. Article 26 of the VCLT: Pacta sunt servanda, Can Yeginsu and Patrick Pearsall6. Article 27 of the VCLT: Internal law and observance of treaties, Rumiana Yotova7. Article 28 of the VCLT: Non-Retroactivity of Treaties, Ben Juratowitch KC and Jackie McArthur8. Article 29 of the VCLT: Territorial scope, Emma Lindsay and Philippa Webb9. Article 30 of the VCLT: Application of successive treaties relating to the same subject-matter, Sean Aughey10. Article 31 of the VCLT: General rule of interpretation, Andreas Kulick and Panos Merkouris11. Article 32 of the VCLT: Supplementary means of interpretation, Esm'e Shirlow and Michael Waibel12. Article 33 of the VCLT: Interpretation of treaties authenticated in two or more languages, Peter Tzeng13. Parts IV and V of the VCLT: Amendment, invalidity, termination and suspension of investment treaties, Luke Sobota and Amelia Keene14. Article 59 of the VCLT: Termination or suspension of the operation of a treaty implied by conclusion of a later treaty, H'el`ene Ruiz Fabri and Randi Ayman15. Article 60 of the VCLT: Termination or suspension of the operation of a treaty as consequence of its breach, H'el`ene Ruiz Fabri and Randi Ayman16. Article 62 of the VCLT: Fundamental change of circumstances, Makane Mo"ise MbenguePART II: RESPONSIBILITY OF STATES AND INTERNATIONAL ORGANIZATIONS17. Article 4 of the ARSIWA: Conduct of organs of a State, Chester Brown18. Article 5 of the ARSIWA: Conduct of empowered entities, Jorge Viñuales and Oliver Hailes19. Article 6 of the ARSIWA and Article 7 of the ARIO, Jonathan Bonnitcha and Alisha Mathew20. Article 7 of the ARSIWA: Excess of authority or contravention of instructions, Chester Brown21. Article 8 of the ARSIWA: Attribution of conduct instructed, directed, or controlled by a State, Jorge Viñuales and Alina Papanastasiou22. Article 13 of the ARSIWA: International obligation in force for a State, Claudia Annacker and EnikÅ? Horv'ath23. Article 14 of the ARSIWA: Extension in time of the breach of an international obligation, Claudia Annacker and EnikÅ? Horv'ath24. Article 15 of the ARSIWA: Breach consisting of a composite act, Claudia Annacker and EnikÅ? Horv'ath25. Article 20 of the ARSIWA: Consent, Federica Paddeu26. Article 21 of the ARSIWA: Self-defence, Federica Paddeu27. Article 23 of the ARSIWA: Force majeure, Federica Paddeu28. Article 24 of the ARSIWA: Distress, Federica Paddeu29. Article 25 of the ARSIWA: Necessity, Federica Paddeu and Michael Waibel30. Article 26 of the ARSIWA: Compliance with peremptory norms, Federica Paddeu31. Article 27 of the ARSIWA: Consequences of invoking a circumstance precluding wrongfulness, Federica Paddeu32. Part Two, Ch. I and II of the ARSIWA: Remedies, Geraldo Vidigal and Stephanie Forrest33. Articles 49-54 of the ARSIWA: Countermeasures, Martins Paparinskis34. Article 55 of the ARSIWA: Lex specialis, Fernando Lusa BordinPART III: STATE SUCCESSION, SOURCES, AND STATE IMMUNITY35. The procedure for succession to bilateral investment treaties, Arman Sarvarian36. Succession in respect of cession, unification, and separation of States, James Devaney and Christian Tams37. The protection of foreign investment in the law of state succession, Arman Sarvarian38. Article 38 of the ICJ Statute: Sources, Patrick Dumberry39. State Immunity in investment arbitration, August ReinischPART IV: SUBSTANTIVE AND PROCEDURAL ASPECTS OF GENERAL INTERNATIONAL LAW IN INTERNATIONAL INVESTMENT LAW40. Cross-cutting substantive aspects: NAFTA standards in light of the decisions of international courts and tribunals, Jingyuan Zhou and Sergio Puig41. Denial of justice, Jarrod Hepburn42. The international law minimum standard of treatment, Rob Howse43. Cross-cutting procedural powers of international courts and tribunals, Cameron Miles44. Nationality, Chiara Giorgetti45. Abuse of process, R'egis Bismuth46. Unjust enrichment, Kathleen ClaussenIndex