Issue-conflict challenges are difficult because the alleged problem is often an arbitrator’s state of mind. Direct evidence of prejudgment is rare. A party therefore has to build an objective case from external facts: writings, prior decisions, overlapping proceedings, public statements, professional roles and the relationship between those circumstances and the issue to be decided.
The case law suggests a consistent practical lesson. Successful challenges are usually not based on a single weak indicator. They create an overall appearance of bias by placing several facts into a coherent context. The question is cumulative: what would a reasonable and informed third person conclude after seeing the full picture?
Start With the Exact Issue Allegedly Prejudged
A challenge should begin by defining the disputed issue narrowly. Saying that an arbitrator has views on “expropriation”, “denial of justice”, “MFN clauses” or “jurisdiction” is normally too broad. Those are fields of law, not necessarily issues that can meaningfully be prejudged.
The stronger formulation identifies a specific proposition that will materially affect the case: for example, whether a particular statutory provision constitutes consent to arbitration, how a specific treaty clause operates in a defined factual setting, or whether a procedural measure has a particular legal effect.
Build the Factual Matrix, Not a List of Complaints
The most persuasive challenges organise the evidence around one theory. In CC/Devas, prior decisions became more significant when combined with a later publication showing persistence of the same view. In Caratube, prior participation became compelling because the two cases shared a respondent, closely related claimants, overlapping facts and relevant prior knowledge. In Perenco, the precise language of a public statement and its connection to pending issues were central.
By contrast, challenges often fail where each circumstance is considered in isolation and none clearly connects the arbitrator to prejudgment of the current issue. The goal is therefore to demonstrate a cumulative or “synergy” effect: each fact reinforces the significance of the others.
Evidence for Different Types of Issue Conflict
Academic writings
Writings are most useful when they are specific, repeated and connected to the current issue. General articles normally carry little weight. Research should focus on consistent statements over time, especially where the arbitrator defended the same position after contrary authority or criticism.
Prior or parallel proceedings
The key evidence is the degree of identity between the proceedings. Compare parties, legal provisions, facts, witnesses, experts and documents. Prior access to evidence that will reappear in the current arbitration can materially strengthen the challenge.
Public statements
Preserve the exact wording, date, medium and context. A dry procedural comment is different from categorical language suggesting that liability, jurisdiction or another contested issue has already been resolved. The 2024 IBA Orange List expressly recognises public advocacy of a position on the case as potentially relevant.
Double-hatting and role conflict
Show how the external professional role creates an incentive to favour the same legal position. It is not enough to show that the arbitrator is busy in multiple roles. The challenge should connect the other role to the issue in the pending case and explain why the outcome of one proceeding could matter in the other.
Use the IBA Guidelines as a Framework, Not as a Substitute for Analysis
The IBA Guidelines are frequently cited because they provide a common vocabulary for conflicts. They can make a challenge easier to organise and may give a decision-maker a recognised reference point. They are particularly useful for distinguishing between a general prior legal opinion, a related prior proceeding and case-specific public advocacy.
But the Guidelines are not automatically decisive. Successful challenges such as Caratube and CC/Devas were not dependent on applying a particular IBA List item. Conversely, falling within an Orange List situation does not automatically require disqualification. The underlying General Standards and the facts remain controlling.
The Applicable Standard Matters
A party should identify the legal standard before drafting the challenge. Under UNCITRAL-style and many institutional rules, the central question is whether the circumstances give rise to justifiable doubts from the standpoint of a reasonable third person. ICSID Convention arbitration retains the language of “manifest lack” in Article 57, although current ICSID guidance describes the applicable test as objective and based on a reasonable third-party evaluation of the evidence.
The standard affects how the evidence should be presented. The more demanding the perceived threshold, the more important it is to avoid speculative inferences and demonstrate a concrete connection between the alleged predisposition and a material issue in the case.
Do Not Confuse Adverse Decisions With Bias
Parties sometimes challenge arbitrators after an unfavourable procedural order, arguing that the tribunal has prejudged the merits. Such challenges generally fail unless the decision or conduct actually reveals prejudgment. An adverse ruling on document production, bifurcation, jurisdictional sequencing or another procedural matter is not itself evidence of partiality.
A challenge should therefore distinguish between disagreement with a decision and evidence that the arbitrator has closed their mind. Without that distinction, the challenge can appear tactical and may undermine the credibility of stronger grounds.
A Practical Evidence Checklist
- The exact issue allegedly prejudged and why it is material.
- The arbitrator’s precise words, decisions or conduct relied upon.
- Chronology of prior statements, appointments and proceedings.
- Comparison table of parties, legal provisions, facts, witnesses and evidence across related cases.
- Any prior access to confidential or case-specific information relevant to the current dispute.
- Professional roles that create a possible incentive to maintain the same position elsewhere.
- Relevant disclosure statements and any inconsistencies or omissions.
- Applicable rule, challenge deadline and decision-maker.
- Relevant IBA Guidelines provisions and any other applicable code of conduct.
- A short explanation of the cumulative appearance created by all circumstances taken together.
How to Structure the Written Challenge
- State the legal standard and deadline first.
- Define the precise issue said to have been prejudged.
- Set out a neutral chronology of the relevant facts.
- Present primary evidence, with quotations kept short and contextualised.
- Explain the connection between each fact and the alleged prejudice.
- Address obvious counterarguments, including expertise, the ability to decide de novo and differences between prior cases.
- Apply the reasonable third-person test to the cumulative factual matrix.
- Request the remedy without overstating the case or attacking the arbitrator personally.
What the Leading Cases Teach
CC/Devas teaches that a prior view becomes more significant when its consistency and persistence can be demonstrated. Caratube teaches that extensive factual overlap and prior exposure to relevant evidence can transform a similar prior case into a genuine impartiality concern. Telekom Malaysia and Blue Bank show that a conflicting professional role can substitute for factual identity where the same legal issue is being advanced in another capacity. Perenco shows that exact language and context matter when the arbitrator comments publicly on the pending dispute.
The failed challenges are equally instructive. Urbaser and Belokon demonstrate that general scholarship or broad legal concepts are usually insufficient. Tidewater illustrates that substantial overlap may still fail where the decision-maker is not persuaded that the arbitrator has lost the ability to reconsider the issue independently. Procedural-order challenges such as BSG and PNB Bank show the weakness of speculative allegations of prejudgment.
Conclusion
The key to an issue-conflict challenge is not the number of alleged circumstances but the quality of the connection between them. The party should show a concrete risk of prejudgment, define the disputed issue precisely, and demonstrate an overall appearance of bias through a coherent factual matrix. The IBA Guidelines and applicable codes can support the analysis, but the decisive question remains contextual: would a reasonable and informed third person conclude that the arbitrator may be influenced by a previously fixed position rather than by the merits of the case as presented?
Selected authorities
- CC/Devas (Mauritius) Ltd. and others v. Republic of India, PCA Case No. 2013-09, Decision on Challenge (30 September 2013).
- Caratube International Oil Company LLP and Devincci Salah Hourani v. Kazakhstan (II), ICSID Case No. ARB/13/13, Decision on Disqualification (20 March 2014).
- Perenco Ecuador Limited v. Ecuador, ICSID Case No. ARB/08/6, Decision on Challenge (8 December 2009).
- 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).
- BSG Resources Limited and others v. Guinea, ICSID Case No. ARB/14/22, Decision on Proposal to Disqualify All Members of the Tribunal (28 December 2016).
- AS PNB Banka and Others v. Latvia, ICSID Case No. ARB/17/47, Decision on Proposals to Disqualify (16 June 2020).
