The UNCITRAL Code of Conduct for Arbitrators in International Investment Dispute Resolution (the “UNCITRAL Code of Conduct”) recalibrates ethical expectations in investor-state dispute settlement.
Adopted in 2023 under UN General Assembly Resolution 78/105 after six years of work in UNCITRAL Working Group III, it is a voluntary soft law instrument.[1] Accordingly, it sets recommended standards of conduct for arbitrators.[2] In addition, UNCITRAL published the final code for arbitrators in February 2024, thereby improving the accessibility and usability of the text.
The UNCITRAL Code of Conduct aims to harmonise ethical standards for arbitrators and respond to longstanding concerns regarding the legitimacy of the ISDS system.[3]
More specifically, it is structured in twelve articles covering scope, independence and impartiality, limits on multiple roles, diligence and integrity, restrictions on ex parte communication, confidentiality, disclosure obligations, and compliance.
Independence and Impartiality: The Operative Baseline
Article 3 of the UNCITRAL Code of Conduct requires arbitrators to be independent and impartial from appointment to the end of the proceeding.[4]
The first paragraph sets the overarching duty. The second provides an illustrative, non-exhaustive list of situations that can place compliance in doubt.[5]
These situations include being influenced by loyalty to a disputing party or another person, taking instructions from a government, organization, or individual on matters in the proceeding, and using the position to advance personal financial or private interests.[6]
Article 3 also targets the appearance of bias.[7] In other words, a failure to act, including incomplete or outdated disclosures, can be sufficient to raise concern.[8] As a result, the standard is objective and asks whether a reasonable third person, informed of the relevant facts and circumstances, would have justifiable doubts.[9]
Multiple Roles and Double-Hatting
Article 4 of the UNCITRAL Code of Conduct restricts “double-hatting” by preventing an arbitrator from acting concurrently as counsel or expert in proceedings involving the same measures, the same or related parties, or the same provisions of the same instrument of consent.[10]
In parallel, Article 4 introduces a cooling-off framework that begins when the mandate ends, including after a final award, resignation, or disqualification.[11]
Under this framework, a former arbitrator may not act as counsel or expert for three years in disputes involving the same measures, or the same or related parties.[12] Likewise, a former arbitrator is also restricted for one year in disputes involving the same treaty provisions under the same instrument of consent.[13]
The restriction is one way, from arbitrator to counsel or expert. However, the disputing parties may waive it by agreement.[14]
In practice, Article 4 protects the process. It reduces incentives to shape decisions with future advocacy work in mind. At the same time, it gives parties a clearer conflicts screen at the appointment stage.
Disclosure
Article 11 of the UNCITRAL Code of Conduct mandates extensive disclosures.[15] It includes relationships and appointments within the past five years involving disputing parties, legal representatives, and expert witnesses.[16] Moreover, the duty is continuing and must be updated promptly.[17]
The Code adopts a when in doubt, disclose posture by requiring disclosure of any circumstances likely to give rise to justifiable doubts as to independence or impartiality.[18]
In Rutas de Lima v. Municipalidad Metropolitana de Lima, Article 11 was invoked to argue that the arbitrators had a continuing duty to disclose a development said to be relevant to independence and impartiality.[19] However, the challenge failed on procedural timing under the applicable challenge deadline, rather than on the final merits.[20]
Procedural Conduct: Diligence, No Delegation, Confidentiality
Article 5 of the UNCITRAL Code of Conduct requires diligence. Arbitrators must devote sufficient time to the case and issue decisions in a timely manner.[21]
Article 6 of the UNCITRAL Code of Conduct further requires integrity and competence. It prohibits arbitrators from delegating their decision-making function to assistants or any other person.[22]
Article 8 of the UNCITRAL Code of Conduct imposes confidentiality. Arbitrators may not disclose deliberations or draft decisions, and the duty continues after the mandate ends.[23]
Meanwhile, Article 7 prohibits ex parte communications, subject to limited exceptions.[24] For arbitrators, an exception may exist where permitted by the instrument of consent, applicable rules, or party agreement.[25] A further exception may apply to pre-appointment interviews, strictly limited to expertise and availability.[26]
Ex parte communication refers to “any communication” concerning the dispute with a party or its legal representative.[27] In addition, it extends to an “affiliate, subsidiary or other related person”, such as a parent company or a third-party funder.[28] It is ex parte when it occurs “without the other disputing party or its legal representative being present” or “having knowledge of the communication taking place.”[29]
“Presence” and “knowledge” are interpreted functionally. They can be satisfied through remote participation, or through adequate notice and a genuine opportunity to take part.[30]
Finally, even where the framework permits an ex parte exchange, the exchange must not address procedural or substantive issues in the proceeding, or issues reasonably anticipated to arise.[31]
Compliance: Where the Teeth Come from
Enforcement of the UNCITRAL Code of Conduct is driven by the procedural framework applicable to the dispute. Any challenge, disqualification, or other sanction is governed by the instrument of consent or the applicable arbitration rules.[32]
As a voluntary soft law text, the Code is typically made operational through the arbitrator’s written undertaking.[33] Candidates and arbitrators are expected to sign a declaration confirming they have read the Code and “undertake to comply with it”.[34]
The UNCITRAL Code of Conduct is intended to operate alongside treaty-based conduct provisions. Where there is direct incompatibility and compliance with both is not possible, the instrument of consent, of course, prevails.[35]
The lawyers and arbitrators of Aceris Law regularly serve in international arbitration and investor-state dispute settlement proceedings and are prepared, at the outset of any appointment, to agree to be bound by the UNCITRAL Code of Conduct for Arbitrators, including its standards on independence, impartiality, disclosure, and restrictions on multiple roles.
[1] Resolution 78/105 on a Code of Conduct for Arbitrators in International Investment Dispute Resolution; N. Kamau, UNCITRAL Code of Conduct for Arbitrators in International Investment Dispute Resolution, 2024(1) b-Arbitra 273, p. 273; UNCITRAL Code of Conduct, Article 2.2.
[2] Paris Court of Appeal, 1 July 2025, Oschadbank v. Russian Federation (I), no. 24/05336, para. 105.
[3] N. Kamau, UNCITRAL Code of Conduct for Arbitrators in International Investment Dispute Resolution, 2024(1) b-Arbitra 273, p. 276.
[4] M. Potesta and L. Zinnerman in M. Potesta and C. Giorgetti (eds.), The UNCITRAL Code of Conduct for Arbitrators in International Investment Dispute Resolution: An Article-by-Article Commentary (2025), p. 32.
[5] UNCITRAL Code of Conduct, Article 3.2; M. Potesta and L. Zinnerman in M. Potesta and C. Giorgetti (eds.), The UNCITRAL Code of Conduct for Arbitrators in International Investment Dispute Resolution: An Article-by-Article Commentary (2025), p. 36.
[6] UNCITRAL Code of Conduct, Article 3.2.
[7] UNCITRAL Code of Conduct, Article 3.2(f) (“Take any action that creates the appearance of a lack of independence or impartiality.”).
[8] UNCITRAL Code of Conduct, Article 3.2(f); M. Potesta and L. Zinnerman in M. Potesta and C. Giorgetti (eds.), The UNCITRAL Code of Conduct for Arbitrators in International Investment Dispute Resolution: An Article-by-Article Commentary (2025), p. 45.
[9] UNCITRAL Code of Conduct, Article 3.2(f); M. Potesta and L. Zinnerman in M. Potesta and C. Giorgetti (eds.), The UNCITRAL Code of Conduct for Arbitrators in International Investment Dispute Resolution: An Article-by-Article Commentary (2025), p. 45.
[10] UNCITRAL Code of Conduct, Article 4.1; C. Giorgetti in M. Potesta and C. Giorgetti (eds.), The UNCITRAL Code of Conduct for Arbitrators in International Investment Dispute Resolution: An Article-by-Article Commentary (2025), p. 58.
[11] UNCITRAL Code of Conduct, Articles 4.2, 4.3, 4.4; N. Kamau, UNCITRAL Code of Conduct for Arbitrators in International Investment Dispute Resolution, 2024(1) b-Arbitra 273, p. 274.
[12] UNCITRAL Code of Conduct, Articles 4.2, 4.3; C. Giorgetti in M. Potesta and C. Giorgetti (eds.), The UNCITRAL Code of Conduct for Arbitrators in International Investment Dispute Resolution: An Article-by-Article Commentary (2025), p. 60.
[13] UNCITRAL Code of Conduct, Article 4.4; C. Giorgetti in M. Potesta and C. Giorgetti (eds.), The UNCITRAL Code of Conduct for Arbitrators in International Investment Dispute Resolution: An Article-by-Article Commentary (2025), p. 60.
[14] C. Giorgetti in M. Potesta and C. Giorgetti (eds.), The UNCITRAL Code of Conduct for Arbitrators in International Investment Dispute Resolution: An Article-by-Article Commentary (2025), pp. 60, 64.
[15] UNCITRAL Code of Conduct, Article 11.
[16] UNCITRAL Code of Conduct, Article 11.2(d).
[17] C. Brown in M. Potesta and C. Giorgetti (eds.), The UNCITRAL Code of Conduct for Arbitrators in International Investment Dispute Resolution: An Article-by-Article Commentary (2025), p. 181.
[18] UNCITRAL Code of Conduct, Article 11.5.
[19] Rutas de Lima S.A.C v. Municipalidad Metropolitana de Lima (III), PCA Case No. 2023-34, Decision on Challenge to Prof. Radicati Di Brozolo and Prof. Arias, 27 October 2025, para. 53.
[20] Rutas de Lima S.A.C v. Municipalidad Metropolitana de Lima (III), PCA Case No. 2023-34, Decision on Challenge to Prof. Radicati Di Brozolo and Prof. Arias, 27 October 2025, paras. 91-109.
[21] UNCITRAL Code of Conduct, Article 5.
[22] UNCITRAL Code of Conduct, Article 6.
[23] UNCITRAL Code of Conduct, Article 8.
[24] UNCITRAL Code of Conduct, Article 7.
[25] UNCITRAL Code of Conduct, Articles 7.1; A. Sarvarian in M. Potesta and C. Giorgetti (eds.), The UNCITRAL Code of Conduct for Arbitrators in International Investment Dispute Resolution: An Article-by-Article Commentary (2025), p. 111.
[26] UNCITRAL Code of Conduct, Article 7.2; A. Sarvarian in M. Potesta and C. Giorgetti (eds.), The UNCITRAL Code of Conduct for Arbitrators in International Investment Dispute Resolution: An Article-by-Article Commentary (2025), p. 111.
[27] Commentary to the UNCITRAL Code of Conduct for Arbitrators in International Investment Dispute Resolution, Article 1.11; A. Sarvarian in M. Potesta and C. Giorgetti (eds.), The UNCITRAL Code of Conduct for Arbitrators in International Investment Dispute Resolution: An Article-by-Article Commentary (2025), p. 109.
[28] Commentary to the UNCITRAL Code of Conduct for Arbitrators in International Investment Dispute Resolution, Article 1.11; A. Sarvarian in M. Potesta and C. Giorgetti (eds.), The UNCITRAL Code of Conduct for Arbitrators in International Investment Dispute Resolution: An Article-by-Article Commentary (2025), p. 109.
[29] Commentary to the UNCITRAL Code of Conduct for Arbitrators in International Investment Dispute Resolution, Article 1.11; A. Sarvarian in M. Potesta and C. Giorgetti (eds.), The UNCITRAL Code of Conduct for Arbitrators in International Investment Dispute Resolution: An Article-by-Article Commentary (2025), p. 109.
[30] UNCITRAL Code of Conduct, Article 7.3.
[31] Commentary to the UNCITRAL Code of Conduct for Arbitrators in International Investment Dispute Resolution, Article 1.11; A. Sarvarian in M. Potesta and C. Giorgetti (eds.), The UNCITRAL Code of Conduct for Arbitrators in International Investment Dispute Resolution: An Article-by-Article Commentary (2025), p. 109.
[32] UNCITRAL Code of Conduct, Article 12.3.
[33] N. Kamau, UNCITRAL Code of Conduct for Arbitrators in International Investment Dispute Resolution, 2024(1) b-Arbitra 273, p. 276. M. Potesta and L. Zinnerman in M. Potesta and C. Giorgetti (eds.), The UNCITRAL Code of Conduct for Arbitrators in International Investment Dispute Resolution: An Article-by-Article Commentary (2025), p. 25.
[34] UNCITRAL Code of Conduct, Annex 1.
[35] UNCITRAL Code of Conduct, Article 2.2.
