Hong Kong court rejects apparent bias challenge based on arbitrator’s previous writings

The Hong Kong Court of First Instance has dismissed a foreign State’s challenge to an arbitrator in an HKIAC-administered bilateral investment treaty (BIT) investor-State arbitration seated in Hong Kong (R v. C, [2026] HKCFI 4688). 

The respondent State challenged the arbitrator appointed by the claimant investor based on three grounds: the arbitrator’s previous writings on most-favoured nation (MFN) clauses, his multiple appointments in cases against the State, and his connection to the investor’s home State.  The court rejected all three grounds and held, in particular, that the arbitrator’s scholarly writings did not show that he had prejudged the MFN issue in the BIT arbitration.

The judgment demonstrates that, while the Hong Kong courts will scrutinise arbitrator challenges carefully, they will not lightly infer apparent bias from an arbitrator’s academic work, appointments in unrelated arbitrations, or nationality-based connections.

Background

The investor commenced two parallel arbitrations against the State on 31 October 2024: one under the BIT and one under the Energy Charter Treaty (ECT).  Both arbitrations concern measures affecting the investor’s investments in the host State.  The investor appointed the same arbitrator in both arbitrations.

The State challenged the arbitrator’s appointment in both arbitrations on 26 November 2024.  In the BIT challenge, it relied on his previous writings on MFN clauses, his multiple appointments in cases against the State, and his connection to the investor’s home State.  The challenge in the ECT arbitration was dealt with by a PCA-designated appointing authority, which upheld the challenge on the basis that the arbitrator’s concurrent service in the BIT and ECT arbitrations would give rise to justifiable doubts as to his impartiality.  Since the BIT and ECT tribunals were not identically composed, the concern was that the arbitrator might obtain information in one arbitration that would not be available to the members of the tribunal in the other arbitration.  The arbitrator was therefore removed from the ECT proceedings.

The BIT challenge took a different route.  Because the BIT did not specify where, by whom or how an arbitrator challenge was to be decided, the parties initially disagreed on the proper procedure.  They ultimately entered into a procedural agreement under which the BIT arbitration would be administered by the HKIAC, seated in Hong Kong, and the challenge would be decided by the HKIAC.  The procedural agreement also provided that the HKIAC’s decision on the challenge would be final, binding and would not be appealed.  After the HKIAC dismissed the challenge, the State applied to the Hong Kong court under section 26 of the Hong Kong Arbitration Ordinance (Cap. 609) (Arbitration Ordinance) for the challenge to be decided afresh.

Before the court, the investor raised a number of potentially dispositive threshold objections, alongside its responses to the State’s substantive grounds of challenge.

Threshold issues: challenge not time-barred and no waiver or estoppel

On time-bar, the investor had to establish both that a 15-day time limit under the UNCITRAL Rules or the HKIAC Rules applied, and that time ran from receipt of the BIT notice of arbitration by the State’s embassy.  The court rejected the argument, including because it was not accepted that the challenge had initially been brought under the UNCITRAL Rules, it was unclear that the HKIAC Rules applied retrospectively, and time should not run from courier delivery to the State’s embassy.  Instead, the court held that, even if the HKIAC Rules applied retrospectively, time ran from receipt of the notice of arbitration by the State’s Ministry of Foreign Affairs, meaning that the challenge was within time.

The investor also argued that the State was barred by waiver or estoppel from renewing its arbitrator challenge before the court, because the parties’ procedural agreement provided that the HKIAC’s decision on the challenge would be final, binding and not subject to appeal.  The court rejected that argument, holding that the State’s statutory right to ask the court to decide the challenge could not be excluded by agreement. 

Previous writings on MFN: no apparent prejudgment

The State’s central complaint was that the arbitrator had written extensively on MFN clauses and had expressed views said to favour the use of neutrally worded MFN clauses to import broader substantive protections and arbitral jurisdiction from other treaties. 

The court applied the orthodox apparent bias test: whether a fair-minded and informed observer, having considered the relevant facts, would conclude that there was a real possibility of bias.  The court accepted that a prior view on the law is not, without more, a basis for removal; there must be an appearance of prejudgment of an issue on which the parties are entitled to expect an open mind.  It also noted that challenges based on scholarly or professional writings have generally failed, and that the International Bar Association Guidelines on Conflicts of Interest in International Arbitration (IBA Guidelines) do not require disclosure of a previously expressed legal opinion where it is not focused on the subject case.

On the facts, the court held that the arbitrator’s writings were general scholarly writings on MFN issues, not opinions about the present case, the BIT, or the parties.  The court also noted the arbitrator’s more recent writings, which emphasised that MFN clauses should be interpreted treaty by treaty, by reference to text, context, object and purpose, and without presumptions in favour of either States or investors.  The fair-minded and informed observer would therefore not conclude that the arbitrator had prejudged the MFN issue in the BIT arbitration.

Parallel appointments: theoretical risk not enough

Following the arbitrator’s removal from the ECT arbitration, the State’s multiple appointments challenge before the Hong Kong court focused on the arbitrator’s continued appointment in another treaty arbitration against the State.  The State argued that the BIT arbitration and the other treaty claim involved overlapping government measures, events, legal arguments and potential witnesses, creating a risk of prejudgment and informational asymmetry.

The investor noted that the other arbitration involved a different claimant, different treaties, a different investment and different counsel, and that parallel appointments do not of themselves give rise to justifiable doubts. 

The court found the reasoning in Electrabel S.A. v. The Republic of Hungary (ICSID Case No. ARB/07/19, 25 February 2008) sensible and compelling, including the point that investment arbitration would become unworkable if arbitrators were automatically disqualified merely because they had been exposed to similar legal or factual issues in concurrent or consecutive arbitrations.  The court held that the alleged overlap was, at this stage, only a theoretical possibility and insufficient to justify removal, while recognising that the issue could be revisited if circumstances changed.

Nationality: no justifiable doubts

The court also rejected the ground of challenge based on the arbitrator’s nationality, holding that the applicable rules did not prohibit the arbitrator’s appointment, that his research institute role did not cast doubt on his independence or impartiality, and that his previous appointment by the investor’s home State to an ICSID panel could not, without more, create justifiable doubts.  Nor did the investor’s home State’s political position, sanctions, memberships or potential interest in the dispute cast doubt on the arbitrator’s impartiality or independence.

Cumulative assessment of the grounds of challenge

Having rejected each ground of challenge individually, the court also assessed the grounds cumulatively.  The court held that each ground fell “so far below the merit threshold” that combining them did not produce a successful challenge.

Indemnity costs

Consistent with the usual practice that costs in arbitration-related proceedings will generally be awarded on an indemnity basis, the Court ordered that the costs of the Originating Summons (including any costs reserved) be paid by the State to the investor on an indemnity basis.

Comment

This judgment is the latest in a series of decisions in which the Hong Kong courts have rejected attempts to rely on alleged arbitrator bias or lack of independence and impartiality.  In O v. S [2026] HKCFI 4910, COB v. FCB [2026] HKCFI 4162 and MB v. HB [2026] HKCFI 4437, the court considered similar issues in the context of challenges to arbitral awards, applying the same objective fair-minded and informed observer test for apparent bias.  R v. C extends that line of authority to a direct challenge to an arbitrator, confirming that previous writings, parallel appointments and nationality-related connections will not, without more, lightly justify a finding of apparent bias.

Arbitrators in arbitrations seated in Hong Kong can therefore take comfort that academic writings, even strongly expressed writings on issues that may arise in the arbitration, will not usually be enough to ground a successful challenge.  The same applies to parallel appointments and nationality.  Overlap, common subject matter, or State connections may require disclosure and vigilance.  They generally should not, without more, and subject to the applicable rules, justify removal.

The judgment is also a reminder that parties should be cautious before assuming that an institutional decision on an arbitrator challenge can be made effectively final.  Even where the parties have agreed that an arbitral institution’s decision is final, binding and not subject to appeal, the Hong Kong court may still be asked to consider the challenge under section 26 of the Arbitration Ordinance.  Parties seeking to avoid a second review by the court of a specific challenge will therefore need to consider carefully whether, and to what extent (if at all), that can validly be achieved.

Simon Chapman KC and Antony Crockett of Herbert Smith Freehills Kramer appeared for the investor in the court proceedings, assisted by Joris Bertrand (registered foreign lawyer).  Patricia Nacimiento, Adilbek Tussupov, Imogen Kenny-Bartlett, Lara Panosch and Theo Pauthonier act for the investor in the underlying arbitrations