Key takeaway

The Commercial Court's decision in E v F [2026] EWHC 1493 (Comm) confirms that a party who challenges an arbitral award within the statutory 28-day window does not buy itself a longer runway to amend that challenge later. In E v F, an amendment application brought 162 days after the award, more than five times the statutory deadline, was refused, even though the amendment did not raise a new ground of challenge and even though the original challenge had been filed in time. The message is clear: get the challenge right the first time.

What happened in E v F?

The case concerned a State's challenge to an award made against it in an investment treaty arbitration. The award was issued on 31 July 2025. The State brought proceedings under sections 67 and 68 of the Arbitration Act 1996 on 27 August 2025, comfortably within the 28-day period set by section 70 of the Act.

The difficulty arose later. On 9 January 2026, over five months after the award, the State applied to amend its claim. F opposed several of the proposed amendments. The State argued that, because it already had a validly issued, in-time challenge before the court, the usual restrictions on extending time should apply less strictly to the amendment. Knowles J disagreed.

Challenging arbitral awards: why does the 28-day deadline matter?

Section 80(5) of the Act gives the court a discretion to extend the 28-day time limit. That discretion is governed by the well-established Kalmneft factors, first set out by Colman J in Kalmneft JSC v Glencore International AG [2001] EWHC QB 461 and refined by Popplewell J (as he then was) in Terna Bahrain Holding Co WLL v Al Shamsi [2012] EWHC 3282 (Comm).

The primary considerations are the length of the delay, whether the party acted reasonably in allowing the deadline to pass, and whether the other side or the tribunal contributed to it. The court will also weigh irremediable prejudice to the respondent, the impact on any ongoing arbitration, the strength of the application, and whether refusal would be unfair in the broadest sense.

Read our article on enforcing and challenging arbitral awards in England and Wales for a broader overview of the routes available when a party seeks to enforce or challenge an arbitral award.

Late amendments to arbitration challenges: why does an in-time claim not make amendment easier?

Knowles J held that these factors apply with equal force to an amendment application as to an original challenge, even where the amendment introduces no new ground. The existence of an in-time claim is relevant, but it does not lower the bar.

As the judgment put it, treating an in-time challenge as an automatic passport to late amendment would only encourage parties to file a single weak point before the deadline and then bring “a major wide ranging set of challenges” by amendment once the pressure was off. That is precisely the sort of tactical delay section 70 is designed to prevent.

The State's explanation, that new lawyers needed time to get up to speed and that instructions took longer to obtain from a State client, did not persuade the judge that five months of delay was reasonable. It did not help that the State itself described the proposed amendments as “refinements” and “developments of points already pleaded” rather than anything genuinely new. Having characterised the amendments that way, it was difficult for the State to then argue that refusing them would be unfair.

Is the 28-day deadline for challenging an arbitration award ever extended?

Extensions have been granted, chiefly where the delay is bound up with fraud.

In Minister of Finance (Incorporated) v International Petroleum Investment Co [2021] EWHC 2949 (Comm), a challenge brought 511 days late was allowed to proceed. The consent award in question was said to have been procured through the dishonest conduct of Malaysia's former Prime Minister, Najib Razak, who controlled the applicant state entities at the time.

A challenge alleging his own fraud was, realistically, impossible while he remained in power, so that period of delay was excused by agreement between the parties. Mr Justice Andrew Baker was critical of the further period of delay after Mr Najib left office, but held it would be unjust to shut the applicant out entirely.

In Celtic Bioenergy Ltd v Knowles Ltd [2017] EWHC 472 (TCC), the applicant only discovered after the award was issued that the respondent had withheld correspondence directly undermining its case. Mrs Justice Jefford found the award had been obtained by fraud and extended time, holding that the delay flowed directly from that fraud and it would be unfair to deny the challenge a hearing.

The pattern is consistent: where delay is a product of the other side's concealment or dishonesty, the court will look past it. Where delay is a product of a party's own organisational or resourcing difficulties, however understandable, it will not.

Read our article on the Arbitration Act 2025 and freezing orders in support of arbitration for related discussion of the English courts’ supportive but disciplined approach to arbitration.

What does E v F mean for arbitration award challenges?

E v F is a warning against treating an in-time challenge as a placeholder to be tidied up later. If there is any prospect that further grounds, evidence, or refinements may be needed, that work should be done before the 28-day deadline expires, not after.

A challenge built on a single point, with the intention of broadening it once instructions catch up, is a strategy this decision leaves exposed.

Anyone considering a challenge to an English-seated arbitral award should treat the 28 days as running from the moment the award, or any relevant correction or appeal decision within the arbitration, is issued. Advice should be sought immediately, and the full scope of the challenge should be identified and pleaded from the outset.  

Barnes Law’s Arbitration team advises clients on challenging arbitral awards, section 67 jurisdiction challenges, section 68 serious irregularity claims, award enforcement, arbitration strategy and urgent arbitration-related court applications. For more information, please contact our Arbitration solicitors in London to discuss how we can support you.

Written by Barnes Law Managing Partner Yulia Barnes.