“Double-hatting” describes the performance of multiple professional roles by the same individual in the arbitration field, most commonly acting as an arbitrator in one dispute while acting as counsel or expert in another. Multiple roles do not always create a conflict. The concern becomes acute when the two matters overlap and the professional duties attached to one role may influence the person’s conduct in the other.
This is sometimes described as role conflict. When the overlapping cases also involve the same legal issue, role conflict can become a form of issue conflict: the arbitrator may have an incentive to adopt a position that supports a client or argument advanced in the other proceeding.
Why Double-Hatting Can Create an Issue Conflict
An arbitrator is expected to remain neutral and decide the case on the submissions and evidence presented. Counsel has a different duty: to advance the client’s position. Where the same individual performs both roles in matters involving the same legal issue, the two responsibilities can pull in different directions.
The concern is not necessarily conscious misconduct. The problem is structural. A reasonable observer may question whether the arbitrator can decide one case without considering the consequences for an argument being advanced on behalf of a client in another case.
Telekom Malaysia: The Classic Role-Conflict Case
In Republic of Ghana v. Telekom Malaysia, Professor Emmanuel Gaillard was serving as arbitrator while acting as counsel in another arbitration, RFCC v. Morocco. Both proceedings involved a related expropriation issue.
The District Court of The Hague emphasised the incompatibility between the duties of counsel and arbitrator in the overlapping circumstances. Counsel must present all arguments that advance the client’s interests, whereas the arbitrator must remain independent and impartial. The court gave Professor Gaillard an opportunity to choose between the two roles; he ultimately withdrew as counsel in the other matter.
The decision is important because the factual identity between the two disputes was limited. The legal overlap and the conflicting professional roles were enough to generate the concern.
Blue Bank: Law-Firm Roles Can Matter
In Blue Bank v. Venezuela, arbitrator José María Alonso Puig was a partner in Baker & McKenzie and a member of the firm’s global arbitration leadership, while other offices of the same firm represented an investor in another arbitration against Venezuela involving similar issues.
The challenge was upheld. The decision considered the arbitrator’s equity partnership, the cooperation between offices of the global firm and the similarity of issues. The case demonstrates that role conflict is not limited to the arbitrator personally appearing as counsel in the parallel proceeding; the structure and integration of the arbitrator’s firm may also be relevant.
When Double-Hatting Does Not Equal Issue Conflict
It is important not to treat every multiple role as issue conflict. An arbitrator may act as counsel in an entirely unrelated dispute without any meaningful overlap. Likewise, repeated appointments by one party or counsel may raise independence or party-bias concerns rather than issue bias. The analysis should identify the specific way in which the external role could influence a material issue in the pending arbitration.
Weak challenges often rely on a remote professional connection without establishing a concrete legal or factual overlap. Decisions concerning former government roles, funding-related roles or relatives in another proceeding illustrate that an abstract possibility of influence is usually insufficient without evidence connecting the role to the issue before the tribunal.
The 2023 UNCITRAL Code of Conduct and Multiple Roles
The regulatory landscape has changed significantly since many of the leading double-hatting cases were decided. The UNCITRAL Code of Conduct for Arbitrators in International Investment Dispute Resolution, adopted in 2023, expressly addresses multiple roles where the Code applies.
Article 4 limits an arbitrator from acting concurrently as a legal representative or expert witness in another proceeding in specified overlapping circumstances. The commentary explains that the restrictions are triggered where the other proceeding involves, for example, the same measures, the same or related parties, or the same provisions of the same instrument of consent. The Code also provides post-service restrictions for certain roles and periods.
This is a major development because double-hatting is no longer addressed only through general principles of impartiality and case-by-case challenges. In applicable investor-State proceedings, it is also subject to a dedicated conduct rule.
The IBA Guidelines and Related Roles
The 2024 IBA Guidelines also contain several Orange List situations relevant to role conflicts, including service in another arbitration on a related issue involving a party, repeated appointments, co-counsel relationships, and certain relationships between an arbitrator’s firm and participants in another related dispute. These provisions are useful for disclosure analysis but should be read together with the General Standards.
Double-Hatting in Commercial Arbitration
Although recent regulatory reform has focused heavily on investor-State arbitration, role conflict is equally capable of arising in commercial arbitration. Telekom Malaysia itself is a prominent example. The risk may be particularly acute in specialised practice areas where the same small group of lawyers repeatedly acts as arbitrators and counsel on recurring legal or technical issues.
Some specialist systems go further. Sports arbitration has long imposed particular restrictions on arbitrators acting as counsel before the same institution, illustrating that a community can adopt structural rules where repeated overlapping roles create persistent legitimacy concerns.
Practical Assessment of a Double-Hatting Concern
- Identify each professional role performed by the arbitrator, the arbitrator’s firm and closely connected practitioners.
- Determine whether the roles are concurrent or recent enough to remain relevant.
- Compare the legal issues in the two matters and identify any identical treaty, contractual or statutory provisions.
- Compare the parties, affiliates, measures and factual background.
- Ask whether the arbitrator’s decision in one case could materially support or undermine an argument advanced in the other.
- Check the applicable arbitration rules, the 2024 IBA Guidelines and, for investor-State disputes, whether the 2023 UNCITRAL Code of Conduct applies.
- Analyse disclosure separately from disqualification: a role may need to be disclosed even if it does not ultimately justify removal.
Conclusion
Double-hatting becomes most problematic when professional roles intersect with a material issue. Telekom Malaysia and Blue Bank demonstrate that role conflict can create an appearance of bias even without identical facts. The 2023 UNCITRAL Code of Conduct has now converted part of this concern into an express rule for applicable investor-State proceedings, while the 2024 IBA Guidelines continue to provide a broader disclosure and conflicts framework. The practical question remains the same: does the overlapping role give the arbitrator a reason, or appear to give the arbitrator a reason, to favour a legal position for purposes beyond the case being decided?
Selected authorities
- Republic of Ghana v. Telekom Malaysia Berhad, District Court of The Hague (18 October 2004).
- Blue Bank International & Trust (Barbados) Ltd. v. Venezuela, ICSID Case No. ARB/12/20, Decision on Disqualification (12 November 2013).
- Tidewater Investment Srl and Tidewater Caribe, C.C. v. Venezuela, ICSID Case No. ARB/10/5, Decision on Challenge (23 December 2010).
- UNCITRAL Code of Conduct for Arbitrators in International Investment Dispute Resolution (2023), Article 4.
