Revisiting Halliburton -v- Chubb: arbitrator impartiality and duties of disclosure

Halliburton Company v Chubb Bermuda Insurance Ltd [2020] UKSC 48 (27 November 2020)

The 2020 Supreme Court decision in this case addressed two key issues. Firstly, whether and to what extent an arbitrator can accept appointments in multiple references concerning the same or overlapping subject matters with only one common party, without appearing to be biased. Secondly, what, if any, disclosure the arbitrator needs to make to the parties concerned about such appointments.

The Supreme Court confirmed that there is a legal duty of disclosure of any circumstances that might give rise to justifiable doubts as to an arbitrator’s impartiality. This duty might include the disclosure of multiple appointments in overlapping references, depending on the nature of the arbitration and the circumstances of the particular case.

The Supreme Court usefully set out the applicable principles relating to the duty to disclose, examined the relationship between arbitral confidentiality and disclosure and emphasised that context is key to deciding whether the duty has been breached.

It also highlighted that even if the duty to disclose has been breached in a particular case, the Court might decide not to remove the arbitrator if it cannot be concluded objectively that there is any justifiable doubt as to his or her impartiality.

The importance of the Supreme Court’s ruling for London-seated arbitration, and indeed the international arbitral community, is reflected by the fact that the LMAA, GAFTA, LCIA, ICC and CIArb all intervened in the Supreme Court proceedings, although they did not speak with one voice.

One outcome of this case has been the codification, in s.2 of the Arbitration Act 2025, of a mandatory, continuing statutory duty for arbitrators to disclose any circumstances of which they are aware that might reasonably give rise to justifiable doubts as to their impartiality.

In this article, we look back at the Supreme Court’s findings and their subsequent application in recent cases.

The background facts

The case concerned an arbitration under a Bermuda Form liability policy which arose out of the damage caused by the explosion and fire on the Deepwater Horizon drilling rig in the Gulf of Mexico in 2010 when a well was being plugged in the context of a temporary abandonment.

BP Exploration and Production Inc (BP) was lessee of the drilling rig. Transocean Holdings LLC (Transocean) owned the rig and had contracted with BP to provide crew and drilling teams. Halliburton Company (Halliburton) provided cementing and well-monitoring services to BP in relation to the temporary abandonment and the plugging of the well.

Numerous claims were brought in the US courts against all three parties. Halliburton and Transocean settled certain of these claims and sought to be indemnified by their insurers, Chubb Bermuda Insurance (Chubb). Halliburton had taken out a Bermuda Form liability policy with Chubb. Chubb was also Transocean’s excess liability insurer. Chubb denied cover under both policies on the ground that the settlements entered into had not been reasonable.

Reference 1

The Bermuda Form policy provided for New York law with English-seated arbitration before a panel of three arbitrators. Halliburton invoked the arbitration clause and appointed their arbitrator (reference 1). Chubb also appointed an arbitrator, but the nominated arbitrators were unable to agree on the choice of the third arbitrator as chairman.

In June 2015, the English Court appointed Mr Rokison as the chairman of the Tribunal. He had been on Chubb’s list of preferred arbitrators but had been objected to by Halliburton. Nonetheless, Halliburton had not appealed the Court’s order.

Before he expressed his willingness to be appointed, Mr Rokison had disclosed to Halliburton and the Court that he had previously acted as an arbitrator in several arbitrations in which Chubb was a party, including as a party-appointed arbitrator nominated by Chubb, and that he was at that time appointed as arbitrator in two pending references in which Chubb was involved. The Court did not treat these appointments as an impediment to his appointment in reference 1.

Reference 2

In December 2015, Mr Rokison accepted appointment as an arbitrator by Chubb in relation to an excess liability claim by Transocean arising out of the same incident (reference 2). The appointment was made on behalf of Chubb by Clyde & Co, who were also Chubb’s solicitors in reference 1.

Before accepting appointment by Chubb in reference 2, Mr Rokison disclosed to Transocean his appointment in reference 1 and in the other Chubb arbitrations which he had disclosed to Halliburton. Transocean did not object. However, Mr Rokison did not disclose to Halliburton his proposed appointment by Chubb in reference 2.

Reference 3

In August 2016 Mr Rokison accepted appointment in another arbitration arising out of the Deepwater Horizon incident as a substitute arbitrator on the joint nomination of the parties in a claim made by Transocean against a different insurer on the same layer of insurance as the claim in reference 2 (reference 3). This proposed appointment was not disclosed to Halliburton.

In November 2013, Halliburton discovered Mr Rokison’s appointment in references 2 and 3 and raised their concerns with him, referring to the IBA Guidelines on Conflicts of Interest in International Arbitration.

Mr Rokison’s response was that he had not considered he was under an obligation under the IBA Guidelines to disclose those appointments but that, with hindsight, it would have been prudent to mention it to Halliburton’s lawyers. He explained that while all three references arose out of the same incident, the issues were different. Nonetheless, he offered to resign from the two Transocean cases if that was required.

Chubb did not agree to the resignation of Mr Rokison as it would cause a hearing to be postponed and result in wasted costs and delay. Halliburton, therefore, sought an order from the Court removing Mr Rokison as arbitrator. Pursuant to s.24(1) of the Arbitration Act 1996 (1996 Act), the Court may intervene to remove an arbitrator if circumstances gave rise to justifiable doubts as to his impartiality.

Halliburton argued among other things that circumstances existed that gave rise to justifiable doubts as to his impartiality, in particular his acceptance of the appointments by Clyde & Co (on behalf of Chubb) in references 2 and 3 and his failure to notify Halliburton or give it the opportunity to object. There was no allegation of actual bias.

Both the Commercial Court and the Court of Appeal dismissed Halliburton’s application to remove the arbitrator in question on the grounds of apparent bias.

The Supreme Court decision

The duty

The Supreme Court unanimously upheld the lower court decisions. In doing so, it made clear there was a legal duty of disclosure under English law, as reflected by s.33 of the 1996 Act, which imposes on the Tribunal a duty to act fairly and impartially between the parties.

The test under English law is objective, namely whether there were facts or circumstances known to the arbitrator that would or might lead the fair-minded observer to conclude that there was a real possibility that the arbitrator was biased.

However, determining whether there was apparent bias would be very fact specific and would depend on the individual circumstances of the case. Furthermore, while an arbitrator had a legal duty to disclose facts or circumstances (such as multiple appointments, or appointments in overlapping references) that might amount to a potential conflict of interest, the parties could agree to dispense with this requirement.

Confidentiality -v- disclosure

As to the duty of arbitral privacy and confidentiality this did not prohibit all forms of disclosure of the existence of a related arbitration in the absence of express consent.

However, the duty of disclosure did not give an arbitrator carte blanche to disclose whatever was necessary to persuade a party that there was no justification for doubts about his or her impartiality. There would be many matters which could not be disclosed without the express consent of the parties to that arbitration.

However, there was a practice in English-seated arbitration of making a confidential disclosure of involvement in an arbitration involving a common party without obtaining the express consent of the parties to the arbitration.

Market practice

The Supreme Court noted that the IBA Guidelines set out good arbitral practices that were recognised internationally. They did not, however, set out legal obligations.

The various arbitral codes to which the Supreme Court was referred reflected the requirement to disclose facts and circumstances pre-appointment that might give rise to justifiable doubts as to an arbitrator’s impartiality.

There was a variety of arbitral practices in relation to the disclosure of multiple appointments in different contexts. For example, in specialist maritime, commodities and sports arbitrations, multiple overlapping arbitrations did not need to be disclosed because it was not a practice that was generally perceived as calling into question an arbitrator’s impartiality or giving rise to unfairness. By agreeing to arbitrate according to, for example, LMAA or GAFTA rules, the parties were taken to have agreed to dispense with this requirement.

Bermuda Form arbitrations

In Bermuda Form arbitrations it was common practice for parties to appoint arbitrators who had experience in interpreting the Bermuda Form policy on repeated occasions, including in arbitrations relating to the same occurrence. It was also not uncommon for Bermuda Form arbitrators to disclose their involvement in prior or current arbitrations involving a common party without disclosing the identity of the other party, or details concerning the arbitration.

However, there was no established custom, or practice, in Bermuda Form arbitrations by which parties could be taken to have accepted that an arbitrator could take on such multiple appointments without disclosure. Therefore, Mr Rokison was in breach of his legal disclosure obligations in not making that disclosure.

On the facts of the case, however, a fair minded and informed observer would not conclude that the failure to disclose gave rise to a real possibility of apparent bias. Consequently, Mr Rokison should not be removed.

Market reaction

The decision was welcomed by the specialist arbitral bodies such as the LMAA and GAFTA, who had argued that specialist arbitrators are limited in number. Therefore, parties to for example shipping, insurance and trade disputes only have a small pool of suitably qualified and experienced arbitrators from which to make appointments.

Furthermore, in such arbitrations, it is common for there to be related, overlapping references where the parties will appoint the same arbitrator in all the references to avoid inconsistent decisions and save costs, particularly where there is a common set of facts. For example, the LMAA Rules specifically provide for this by allowing concurrent references. The LMAA does not require its arbitrators to disclose these appointments, and neither is this required nor expected by the parties.

By contrast, the LCIA, ICC and CIArb had intervened to argue for a more stringent pro-disclosure approach. The LCIA and ICC’s own arbitral rules impose unambiguous obligations regarding arbitrator disclosure which is more consistent with the international ‘gold standard’ approach.

Ultimately, the Supreme Court took a less prescriptive attitude to arbitrators’ duties of disclosure, preferring instead a case-by-case analysis of whether disclosure obligations have been breached and whether apparent bias could be inferred.

In response, the updated IBA Guidelines, adopted in May 2024, widened the standards of disclosure from arbitrators and clarified that the arbitrator must make a subjective assessment with regard to whether a fact or circumstance should be disclosed and must consider all known facts and circumstances when doing so.

Furthermore, s.2 of the Arbitration Act 2025 has codified the legal duty of disclosure as clarified by the Supreme Court. It amends the 1996 Act to add that ‘an arbitrator must, as soon as reasonably practical, disclose to the person any relevant circumstances …’.

The ICC has also amplified its disclosure requirements in the latest ICC Arbitration Rules 2026: see ICC Arbitration Rules 2026: what arbitrating parties need to know | Hill Dickinson.

Subsequent cases

In Newcastle United Football Company Ltd v Football Association Premier League Ltd & Ors [2021] EWHC 349 (Comm) (24 February 2021), the Court decided that the arbitrator’s failure to disclose certain aspects of his relationship with one of the parties was insufficient to establish apparent bias. This was a sports arbitration under the Premier League (PLL) rules and the arbitrator, who was also a barrister, had failed to disclose that he had advised the PLL on four previous occasions and that the PLL’s solicitors had been involved in 12 arbitrations over the previous three years with this same arbitrator. On the facts, the Court decided the arbitrator should not be removed. Among other considerations, only three of the 12 appointments had been by PLL’s solicitors and two had been accepted after the arbitrator had accepted appointment in this case.

In H1 & Anor v W & Ors [2024] EWHC 382 (Comm) (22 February 2024), the Court removed a sole arbitrator. It found that there could be no reasonable objection to the fact that the sole arbitrator knew a number of the factual witnesses and all three of the expert witnesses on one side. That was to be expected in a relatively small and specialist industry (film and TV production). However, the Court decided that there was an appearance of bias, based on the arbitrator’s remarks about the parties’ expert witnesses.

In Aiteo Eastern E & P Company Ltd v Shell Western Supply and Trading Ltd & Ors [2024] EWHC 1993 (Comm) (01 August 2024), however, the Court found that disclosure failures undermined impartiality and remitted the award to the Tribunal. The Court decided there was a real possibility of unconscious bias having regard to the cumulative picture and the combination of arbitral appointments and advisory/expert engagements in question: see Arbitrator bias and award remission | Hill Dickinson.

In V & Anor v K (Re Arbitration Act 1996) [2025] EWHC 1523 (Comm) (19 June 2025), the Court reconfirmed the high threshold for challenging a maritime arbitration award on the basis of apparent bias: see Arbitrator Apparent Bias Allegations Dismissed | Hill Dickinson. This was not a case of multiple appointments in related cases. Rather, it concerned repeated instructions in unrelated arbitrations by the same law firm over a number of years. However, law firms specialising in maritime law will naturally act for many different clients with the inevitability of repeat appointments of individual LMAA arbitrators.

As can be seen from the cases, the Courts have adopted a high hurdle, fact-specific case-by-case approach to deciding whether there is apparent bias that requires their intervention.

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