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Investor-State dispute settlement (ISDS) is a treaty-based route through which a covered foreign investor may bring a claim against the State where it invested. The investor must rely on an applicable investment treaty, and the claim must satisfy that treaty’s conditions and the governing arbitration framework. ISDS is not one universal procedure, and filing a case does not establish that the State breached the treaty.
What is ISDS in an investment treaty?
In treaty-based ISDS, an investor alleges that a host State has violated a protection in an international investment agreement (IIA). An IIA may be a bilateral investment treaty or an investment chapter in a broader treaty. The investor asks an arbitral tribunal to decide the treaty claim and, where available, grant a remedy.
The term is narrower than “investment dispute.” A disagreement about an investment may instead arise under a contract or domestic law. Such a dispute is not treaty-based ISDS merely because an investor and a State are involved. UNCTAD distinguishes cases grounded in an IIA from cases based only on an investment contract or national investment legislation.
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|---|---|---|
| Treaty-based ISDS | An applicable international investment agreement | The investor’s claim relies on treaty protections and the treaty’s framework for State consent to arbitration. The relevant treaty and arbitration rules determine whether the claim can proceed. |
| Contract dispute | An investment contract | The claim depends on the contract and the dispute-resolution terms that apply to it; it is not treaty-based just because a State is a party. |
| Domestic-law dispute | National legislation or other domestic law | The claim is based on domestic law rather than an IIA. UNCTAD’s treaty-based ISDS count does not treat a case based solely on national investment legislation as treaty-based ISDS. |
How does an investment-treaty claim work?
A useful way to understand a treaty-based case is to separate three questions: what protection the investor invokes, whether the State has consented to arbitrate that kind of claim, and which procedural rules govern the case. These are parts of a conceptual map, not a universal filing sequence: treaty language and applicable rules differ.
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1. The investor identifies a treaty protection
The investor alleges that a State measure or conduct violated an obligation in the applicable treaty. The claim must be tied to a treaty obligation; an adverse business outcome by itself does not establish a treaty breach. Which protections apply, and what a claimant must prove, depend on the treaty and the particular facts.
2. The treaty sets the consent framework
A treaty may set out how the State consents to arbitration and the conditions for an investor to use that route. The investor must fall within the treaty’s coverage and satisfy the requirements that apply to the claim. There is no single eligibility test that applies to every treaty, and not every investor or dispute qualifies.
3. The applicable rules govern procedure
The relevant treaty and arbitration framework determine procedural matters. They may address issues such as the conduct of proceedings and how an award is made, but the applicable provisions vary. A notice period, local-remedy requirement, tribunal appointment method, review route or enforcement rule should not be assumed without checking the actual instruments governing the case.
An arbitration is a process for deciding the claim, not a finding that a treaty was breached. The tribunal’s decision and any remedy depend on the applicable law and the case; a claimant does not win merely by bringing a case.
How many treaty-based ISDS cases are known?
UN Trade and Development (UNCTAD) counts publicly known treaty-based proceedings. Its totals are snapshots, not a guarantee that every filed case is public or included. UNCTAD also notes that counts can be revised when cases that were confidential at filing later become public, so figures from different publication dates may not match exactly.
| UNCTAD snapshot | Reported figure | How to read it |
|---|---|---|
| Through the end of 2023, reported in 2024 | 1,332 known cases; 60 new arbitrations initiated in 2023 | Historical count in UNCTAD’s 2024 facts-and-figures note. |
| End of 2024, reported in 2025 | 1,401 known cases; 58 known cases initiated in 2024 | A later snapshot. UNCTAD says totals may be revised as previously confidential cases become known. |
| As of 31 December 2025, reported by UNCTAD on 1 April 2026 | 1,463 known treaty-based cases; more than 400 cases initiated during 2020–2025 | The latest dated total in the cited UNCTAD update; it counts known cases rather than every possible investor-State dispute. |
| Status within the 1,463 cases, Navigator updated 31 December 2025 | 311 pending; 1,112 concluded; 40 with unknown status | Status categories for that database snapshot. |
Which industries appear in the case statistics?
UNCTAD’s 2024 note reported that about one third of treaty-based cases through 2023 involved energy supply and extractive industries. It counted 235 fossil-fuel-related cases and at least 123 renewable-energy proceedings by the end of 2023. These are historical figures for the period stated, not current totals for later years.
Are the rules changing?
Yes, reform is underway, but proposed changes should not be confused with a universal replacement for existing treaty arbitration. Many older investment treaties remain part of the regime, while both treaty drafting and multilateral reform discussions continue.
Newer investment agreements
UNCTAD’s 2025 analysis of IIAs concluded from 2010 to 2024 describes an initial period focused on recalibrating investor protections and dispute settlement, followed from around 2015 by greater emphasis on cooperation and investment facilitation. It reports that investor-State arbitration appears less often in newer agreements, while older, unreformed treaties continue to dominate the regime.
UNCITRAL reform work
The United Nations Commission on International Trade Law (UNCITRAL) gave Working Group III a broad mandate in 2017 to consider possible ISDS reform. Its 2026 work page lists draft procedural and cross-cutting provisions, as well as proposed statutes for permanent and appellate tribunals. These are reform texts and proposals, not a system that automatically governs every case.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.Are ISDS proceedings public?
Transparency depends on the treaty and procedural framework; it is inaccurate to describe all treaty arbitration as either fully public or invariably secret. UNCITRAL’s Arbitration Rules were amended in 2013 to incorporate Rules on Transparency in Treaty-based Investor-State Arbitration. The 2014 United Nations Convention on Transparency in Treaty-based Investor-State Arbitration, also called the Mauritius Convention on Transparency, provides a way to apply transparency obligations to certain older investment treaties concluded before April 2014. UNCITRAL says the Convention entered into force in 2017.
Whether a particular case is covered by transparency rules, and what documents or hearings are public, must be determined from the instruments that apply to that case.
What to check when evaluating a specific case
A general description of ISDS cannot determine whether a particular investor can bring a claim or what the result might be. The relevant treaty and procedural framework need to be read together. Key questions include:
- Legal basis: Is the claim based on an investment treaty, a treaty investment chapter, a contract, domestic law, or more than one of these?
- Coverage: Does the treaty cover this investor, investment, State and measure?
- Obligation: Which treaty protection is alleged to have been breached, and what defenses or exceptions may be relevant?
- Consent and conditions: What does the treaty provide about access to arbitration, and what preconditions apply?
- Procedure and transparency: Which arbitration rules govern, and what do they and the treaty provide about the proceedings and public access?
- Outcome framework: What remedies are available, and what review or enforcement framework applies to an award?
Those answers are treaty- and case-specific. The existence of an ISDS clause alone does not resolve jurisdiction, liability, remedy or how a decision may be challenged or enforced.
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