UNCITRAL rules and the Permanent Court of Arbitration

Rules, not an institution

UNCITRAL describes its Arbitration Rules as a set of procedural rules on which parties may agree ¹. They are used in both ad hoc and administered arbitrations ¹. The Rules include a model arbitration clause, procedures for appointing arbitrators and running proceedings, and rules on the form, effect and interpretation of the award ¹.

The UNCITRAL Model Law is a different text. It is a model for national arbitration law. Most of its provisions apply only where the place of arbitration is in the State that adopted it, and it sets the court route for setting aside an award ⁷. The Rules apply where the parties agree on them ¹.

Which version applies

Transparency in treaty cases

The UNCITRAL Rules on Transparency took effect on 1 April 2014 ⁵. They are procedural rules for making information on treaty-based investor-state arbitrations publicly available ⁵. The Mauritius Convention on Transparency, adopted on 10 December 2014 and in force since 18 October 2017, gives States a way to apply those rules to treaties concluded before 1 April 2014 ⁵. The UN Secretary-General keeps the published information through the UNCITRAL secretariat, which runs the Transparency Registry ⁵.

What the PCA is

The PCA states it was established in 1899 to support arbitration and other forms of dispute resolution between States ². It is an intergovernmental organisation with its headquarters at the Peace Palace in The Hague ². Its About page, which shows no date and was read on 24 October 2026, gives 129 contracting parties ². The PCA's notice of 22 June 2026 on its 2025 Annual Report says Armenia, Moldova and Indonesia acceded in 2025 as its 125th, 126th and 127th Contracting Parties ⁴. The two counts may reflect different dates.

What the PCA does in a case

• Case administration: the PCA states it frequently provides full case administration support in arbitrations under the UNCITRAL Arbitration Rules ³.
• Investor-state support: it frequently supports disputes between investors and States, including Energy Charter Treaty cases under UNCITRAL rules ³.
• Mixed parties: it supports arbitrations involving combinations of States, State entities, international organisations and private parties ³.
• Registry for law of the sea cases: it has acted as registry in 14 arbitrations under Annex VII of the 1982 UN Convention on the Law of the Sea ³.
• Appointing authority: the PCA Secretary-General has special functions on the role of the appointing authority under the UNCITRAL Rules ³.

Caseload figures

The PCA reports that it administered 251 cases in 2025, including 53 newly initiated proceedings, and handled 46 requests relating to its appointing authority services ⁴. Its notice does not break the 2025 total down by case type ⁴.

ICSID handles some UNCITRAL cases too. Its release of 14 August 2026 reports 15 cases under non-ICSID rules in its fiscal year to 30 June 2026, including 12 under UNCITRAL rules ⁶.