Late Amendments To Arbitration Act Challenges Are Subject To Rules On Excessive Delay

The Commercial Court has confirmed that guidelines on extending time for challenges to arbitral awards should also be used to determine applications to make late amendments to such challenges. The anonymised judgment in E v F [2026] EWHC 1493 (Comm) is a reminder to consider the full details of arbitral challenges promptly. Time limits are tight, and will not readily be extended.

Background

In an award of 31 July 2025, an arbitral tribunal (the Tribunal) decided that it had jurisdiction to determine a dispute between the claimants, (referred to as F), and respondent state (the State) under a Bilateral Investment Treaty and the UNCITRAL Rules 1976. The Tribunal awarded compensation to F.

On 27 August 2025, the State brought a claim in the Commercial Court under sections 67 and 68 of the Arbitration Act 1996 (the Act), challenging the Tribunal’s jurisdiction and alleging serious procedural irregularity. Under section 70(3) of the Act, a party has 28 days within which to bring a section 67 or 68 challenge. The State had therefore brought its challenge in time.

On 9 January 2026, the State applied to amend its challenge. This was 162 days after the date of the award. The Commercial Court was asked to determine whether these amendments should be allowed.

Decision

The Court refused the application to amend. 

Section 80(5) of the Act allows the Court to grant an extension of the 28-day period in section 70(3). Notwithstanding that the initial challenge was brought in time, the Court was not persuaded to treat this application to amend differently from an application to extend time for a challenge generally.

The guidelines applicable to an application to extend time are set out in Kalmneft JSC v Glencore International AG [2001] EWHC QB 461 and developed in Terna Bahrain Holding Co WLL v Al Shamsi [2012] EWHC 3283 (Comm). The factors which the court will consider are:

1. the length of the delay – this is judged against the statutory 28-day yardstick;
2. whether, in permitting the time limit to expire and the subsequent delays to occur, the party was acting reasonably in all the circumstances (the applicant should adduce evidence to explain its conduct, and it will be relevant whether the delay was an intentional, informed choice);
3. whether the respondent to the application or the arbitrator caused or contributed to the delay;
4. whether the respondent to the application or the arbitrator caused or contributed to the delay;
5. the strength of the application; and
6. whether it would be unfair to the applicant to deny it the opportunity to have its application determined.

The hearing of the challenges was fixed for June 2027, which the State argued meant no delay would in practice be incurred. However, the Court was unpersuaded that this alone could determine the application to amend. The Court could take into account the circumstance of an existing in-time claim, and of a substantive hearing that would not in practice be delayed by the amendments. But the Kalmneft factors still fall to be applied, and are not adjusted to deal with an application to amend.

A delay of 162 days was very substantial, being five times the statutory 28-day time limit. The weight of this factor could not be overcome, notwithstanding that there would be no irremediable prejudice to the respondent. Time limits are set to bring finality to proceedings, and finality would still be undermined by allowing such late amendments because finality requires that the ‘compass’ of the disputes to be resolved be fixed. The judge concluded that allowing very late amendments would not honour the ‘foundational principle’ in section 1 of the Act, which seeks the fair resolution of disputes by an impartial tribunal without unnecessary delay or expense.

Comment

The timeframe to bring a challenge under the Act is intentionally tight so as to bring finality to disputes. The Commercial Court’s decision that the Kalmneft factors for deciding whether to extend time apply equally to applications to amend brings clarity for parties launching such challenges. It will not suffice to bring a challenge in time with the intention of amending it later once time has allowed more thorough analysis – all grounds of challenge must be ready within the 28-day limit. 

However, the judge in this case did note that there was no restriction on how the State could advance the case it had already pleaded, so if the applicant was right in saying some of its amendments were ‘merely developments of points already pleaded’ or ‘”pure matters of argument” that “could be put in a skeleton”’, the impact of this decision to refuse the amendments may be minimal. Parties should be clear as to whether they genuinely need to amend their pleaded case, which requires permission, or are simply developing points of argument.

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