Court disallows very late amendments to arbitration claim

E v F [2026] EWHC 1493 (Comm) (17 June 2026)

In dismissing an application by a State Party to an investment treaty arbitration to make very late, opposed, amendments to its arbitration claim form, the Court has highlighted that s.1 of the Arbitration Act 1996 (1996 Act) provides that the relevant statutory provisions are founded on the principle that arbitration is intended to achieve the fair resolution of disputes by an impartial tribunal without unnecessary delay or expense.

The Court decided that principle would not be upheld if it allowed amendments requested more than 130 days after the statutory 28-day time limit had expired.

The background facts

In an award dated 31 July 2025 (the Award) made under a Bilateral Investment Treaty (BIT) and the UNCITRAL Rules 1976, an arbitral tribunal (the Tribunal) found, by a majority, that it had jurisdiction in a dispute between the claimants in the arbitration (F) and the respondent in the arbitration (the State). The Tribunal then ordered that the State pay compensation to F.

On 27 August 2025, the State commenced a claim before the Commercial Court challenging the jurisdiction of the Tribunal under s.67 of the 1996 Act and alleging serious irregularity affecting the Award under s.68 of the 1996 Act.

On 9 January 2026, the State applied to amend its claim. F opposed some of the amendments and the Court was asked to consider whether those amendments should be allowed.

S.70 of the 1996 Act imposes a 28-day time limit for challenging an award under ss.67 or 68 of the 1996 Act. However, pursuant to s.80(5) of the 1996 Act, the Court has power to extend time.

The State’s application to amend was well out of time and the applicable principles in such cases have been set out in a number of cases, including Kalmneft JSC -v- Glencore International AG [2001] EWHC QB (461).

The Kalmneft factors are as follows:

1. the length of the delay

2. whether, in permitting the time limit to expire and the subsequent delays to occur, the applicant was acting reasonably in all the circumstances

3. whether the respondent to the challenge or the arbitrator caused or contributed to the delay

4. whether the respondent to the challenge would by reason of the delay suffer irremediable prejudice in addition to the mere loss of time if the amendment were permitted to proceed

5. whether the arbitration has continued during the period of delay and, if so, what impact on the progress of the arbitration or the costs incurred the determination of the challenge sought to be introduced by amendment by the Court might now have

6. the strength of the amendment and

7. whether in the broadest sense it would be unfair to the applicant for him to be denied the opportunity of having the challenge sought to be introduced by amendment determined.

The State submitted that allowing the opposed amendments would not in practice delay the determination of the challenges because the substantive hearing had already been fixed. In addition, the State had brought its substantive challenge within 28 days and was merely seeking to amend the claim after the expiry of the 28 days. The State contended that the Court should adopt a more nuanced approach and take into account all material circumstances when applying the Kalmneft factors.

The Commercial Court decision

The Court stated that the Kalmneft factors were a guide and not a closed list. The framework was provided by the 1996 Act and there was no basis to impose a requirement that the Court should consider all material circumstances over and above the statutory framework.

In this case:

1. the delay was significant: the State sought to amend 162 days after the Award was published

2. on the evidence, the State had not acted reasonably in letting this amount of time to pass

3. neither F nor the arbitrators contributed to the delay

4. on the other hand, F would not suffer irremediable prejudice due to the delay

5. furthermore, the arbitration had not continued during the period of delay

6. it was not possible to determine at an interim stage whether the proposed amendments were strong or weak

7. it would not be unfair to the State to be denied the opportunity of having the matters introduced by the amendments determined.

Taking all the above into consideration, the Court decided that the length of delay, factor (i), outweighed the remaining factors in this case. Finality in the sense of fixing the remaining compass of the disputes to be resolved, was compromised where that compass was extended by amendment.

The Court added that, to allow the amendments at this stage in the present case would not honour the foundational principle, set out in s.1 of the 1996 Act, of "obtaining the fair resolution of disputes by an impartial tribunal without unnecessary delay or expense". The application to make the opposed amendments was, therefore, refused.

Significantly, however, the Court emphasised that this decision did not limit the compass of the case or arguments that the State might advance on its challenges already advanced without the amendments. The Court did not adopt an over-technical approach to statements of case. Issues which were the subject of the proposed amendments that were already raised by the unamended arbitration claim remained open to be pursued in argument by the State.

Comment

Even where the delay in presenting the amendments created no prejudice to F, the Court considered that the State had waited far too long to seek to amend and as the amendments were said by the State’s counsel to be essentially ’refinements’ to existing arguments, there was scope to make such oral arguments as the State wished when the ss.67 and s68 appeals were heard.

Nonetheless, the case highlights the importance of formulating appeal arguments thoroughly and comprehensively from the outset to avoid any need to amend down the line. If, however, amendments are necessary, they should be proposed as soon as possible without unnecessary delay. If a time extension is required, the Court will take into account the length of delay as a key factor when deciding whether or not to permit the amendments.

For more information on how our International Arbitration experts can support you, contact us today.