Late Amendments: English Court Refuses Post-Deadline Expansion Of Challenges To Arbitral Award

The English Commercial Court has confirmed that the Kalmneft factors apply not only to late arbitration challenges, but also to attempts to expand challenges that were originally brought within the statutory time limit 

In E v F [2026] EWHC 1493 (Comm), the Commercial Court considered how the Kalmneft factors (previously discussed here and here) apply where a party seeks to amend section 67 and section 68 challenges that were themselves brought in time. The Court declined to apply any special overlay or relaxation of the Kalmneft test merely because a challenge was already underway and a hearing had been scheduled. It refused the amendments, holding that allowing the applicant to materially expand the scope of its challenge long after the statutory deadline would undermine finality.

Background

In an award dated 31 July 2025, arising from an arbitration under a Bilateral Investment Treaty, an arbitral tribunal held that it had jurisdiction over a dispute between the claimants (F) and the respondent state (the State) and ordered the State to pay compensation to F. On 27 August 2025, the State challenged the award before the English Commercial Court under sections 67 (substantive jurisdiction) and 68 (serious irregularity) of the English Arbitration Act 1996 (the Act).

The challenge was made within the 28-day limit imposed by Section 70(3) of the Act. Section 80(5) of the Act permits an extension of this period on application to the Court. By application dated 9 January 2026, the State applied to amend its challenge. F opposed some of the amendments. The question before the Court was whether the opposed amendments should be allowed despite the delay.

Decision

Both parties referred to the Kalmneft framework, which set out relevant factors for deciding an application to extend time to challenge an arbitral award. The State argued that the Kalmneft factors should be applied with “restraint" in cases such as this, where the challenge had been brought in time, the substantive hearing had been fixed and the proposed amendments would not in practice delay determination.

The Court considered the Kalmneft factors "a guide and not a closed list” and that the Court will consider all material circumstances. Here, the in-time claim and existing hearing date were part of those circumstances. The Court also noted, citing Popplewell J in Terna Bahrain Holding Co WLL v Al Shamsi [2012] EWHC 3282 (Comm), that factors (i), (ii), and (iii) from Kalmneft (each listed below) are the "primary factors".

Applying that framework, the Court dismissed the application, assessing the individual factors as follows:

1. Delay: the amendments were advanced 162 days after the Award, more than five times the 28-day statutory period. This was a very considerable delay.
2.  Reasonableness of the delay: the Court was not persuaded by the State's attempted justifications for the delay by reference to its instruction of new lawyers, conduct of further analysis and time required to obtain internal instructions.
3.  Responsibility for the delay: neither F nor the arbitrators caused or contributed to the delay.
4. Prejudice: F would not suffer irremediable prejudice by reason of the delay.
5. Impact on the arbitration: the arbitration had not continued during the period of delay.
6. Strength of the amendments: the Court found that a review of the amendments did not allow a sufficiently reliable conclusion at the interim stage as to whether they were strong or weak. However, for the purposes of deciding the application only, it accepted the State’s counsel’s characterisation of the claim as a solid claim by a party which is not abusing the system for any collateral advantage.
7.  Broad unfairness: the Court determined that it would not be unfair in the broadest sense for the State to be denied the opportunity to having the matters in the opposed amendments determined.

Turning to the special circumstances relied on by the State, the Court held that the lack of any practical delay to the substantive hearing did not outweigh the significance of the delay itself in raising the amendments. The Court considered that permitting the scope of the challenge to expand by amendment would undermine the finality of the process and conflict with the statutory objective of resolving disputes without unnecessary delay or expense.

Comment

This decision confirms that Kalmneft applies not only to the late filling of a challenge but also to attempts to amend challenges that were themselves brought in time. Even where the proposed amendments would not disrupt an already fixed substantive hearing, the Court treated finality and the statutory scheme as powerful reasons not to permit the scope of the application to be expanded long after the statutory deadline for challenging the award had lapsed. The decision underscores the need to identify and investigate all potential grounds for challenge comprehensively after an award is issued.

That said, the Court suggested its refusal to permit the amendments may not be fatal to the State’s attempt to rely on some of the arguments the amendments raised. Noting that the “Commercial Court does not adopt an over-technical approach to statements of case”, the Court suggested that it remained open to the State to advance at the substantive hearing certain arguments raised in the proposed amendments, if they could be said to have been encompassed in the existing statement of case.

The authors would like to thank Mohammed Al-Ahbabi for his contribution to this post.