The Law of the Seat Triumphant: Clarity and Certainty under Section 6A of the Arbitration Act 2025?

Posted onOctober 14, 2025
Matthew Purcell

The Arbitration Act 2025 (AA 2025), which came into force on 1 August 2025, marks a considered legislative update to the foundational Arbitration Act 1996 (AA 1996) – which arguably needed review.

As the dust has settled, the new Act appears to be more evolution than revolution. However, one provision stands out: Section 1 of the AA 2025 introduces a new default rule by inserting Section 6A into the AA 1996.

This new Section 6A aims to address the complex and often litigated issue of determining the governing law of the arbitration agreement itself. But will it help?

The Pre-6A Landscape: The Complexity of Enka v Chubb

Let’s cast our minds back. Before the AA 2025, common law rules determined the law governing an arbitration agreement in England, dictated by the governing law chosen for the main contract.

This resulted in a hierarchical, often unpredictable, and ultimately controversial, three-stage test, definitively set out by the Supreme Court in the 2020 landmark case,  Enka Insaat Ve Sanayi A.S. v OOO Insurance Company Chubb.

The Problematic Presumption of Implied Choice

In Enka v Chubb, the Supreme Court confirmed the following order of priorities for determining the applicable law:

If the parties expressly chose the law governing the arbitration agreement, that law applies.
If not, an express choice of law for the main contract is usually taken as an implied choice for the arbitration agreement (subject to validation considerations).
Failing that, apply the law with the closest and most real connection—often the law of the seat of arbitration.

The "De-Coupling" Dilemma

The practical effect of this rule was that the law governing the arbitration agreement could be de-coupled from the law of the seat of the arbitration – very far from ideal.

This result introduced several profound issues for litigants:

Uncertainty: Parties choosing London as a neutral, pro-arbitration seat could find themselves exposed to preliminary jurisdictional challenges governed by a foreign law. This could lead to expensive, time-consuming disputes over conflict of laws and the need for expert evidence on foreign law.
Compromised arbitration: The core benefit of choosing a seat in England - access to the robust, pro-arbitration support and minimal-intervention principles of the AA 1996 - was undermined because the enforceability of the agreement itself was judged by potentially less favourable foreign law.
Satellite Litigation: The Enka decision, while intending to clarify, led to a surge in satellite litigation focused on interpreting the elusive "implied choice".

The Post-6A Position: Statutory Clarity and the New Default

The AA 2025 directly addresses the Enka ambiguity by introducing Section 6A into the AA 1996. This new section establishes a clear, mandatory, and internationally aligned statutory default rule.

The text of the new rule (in easy-to-read substance!)

The law applicable to an arbitration agreement is:

(a) the law that the parties expressly agree applies to the arbitration agreement; or
(b) where no such agreement is made, the law of the seat.

For this purpose, a choice of law for the main contract does not constitute an express choice for the arbitration agreement. 

Exception: the default rule does not apply where the arbitration agreement is derived from a standing offer in a treaty or foreign legislation. 

It is thus, fairly simple: if an arbitration agreement does not expressly specify the law which governs it, it will be governed by the law of the seat, not the law governing the main contract. 

The Statutory Hierarchy of Section 6A

Section 6A provides a new, two-part test for determining the governing law of the arbitration agreement:

Express Choice is Paramount: The law applicable to an arbitration agreement is, first and foremost, the law that the parties expressly agree applies to it.
Default to the Law of the Seat: In the absence of such an express agreement, the applicable law shall be the law of the seat of the arbitration.

Crucially, Section 6A(2) explicitly states:

“For the purposes of subsection (1), agreement between the parties that a particular law applies to an agreement of which the arbitration agreement forms a part does not constitute express agreement that that law also applies to the arbitration agreement.”

This simple yet powerful subsection is the legislative reversal of the Enka presumption. The choice of law for the main contract is now completely irrelevant to the governing law of the arbitration agreement, unless it is specifically and separately designated.

Risks and Benefits to Litigants in the Post-6A Era

The introduction of Section 6A is generally welcomed as a positive development, which moves England & Wales and Northern Ireland toward a seat-centric approach seen in many jurisdictions.

Benefits to Litigants

Certainty and Speed: Litigants choosing a seat in England should now have confidence that, absent their express agreement to the contrary, the law governing the existence, validity, and scope of their agreement to arbitrate will be English law. This predictability simplifies risk assessment, especially in multi-jurisdictional contracts.
Reduced Cost and Delay: By eliminating the need to argue over implied choice and, more often than not, removing the requirement for expert evidence on foreign law to address jurisdictional challenges, Section 6A streamlines the start of arbitral proceedings, saving time and considerable cost.
Reinforcement of the English (and Welsh and Northern Island) Seat: The reform firmly links the procedural law (the AA 1996) with the substantive law governing the agreement to arbitrate (English law). This ensures that London-seated arbitrations receive the full, robust support of the English courts and the pro-arbitration policy for which the jurisdiction is globally renowned.
Codified Party Autonomy: While establishing a strong default, Section 6A preserves the fundamental principle of party autonomy. Parties retain the absolute right to specify any law they wish to govern their arbitration agreement; the Act merely provides a logical, jurisdiction-aligned safety net where they fail to do so.

Risks and New Considerations for Litigants

Risk of Inadvertent Application of the Law of the Seat: Inaction is the most significant risk Parties who preferred the old Enka outcome (i.e., they wanted their French-governed main contract to govern their London-seated arbitration agreement) but did not explicitly stipulate this, will now find the arbitration agreement governed by English law by default. This change requires all parties to review and, if necessary, amend existing arbitration clauses in light of the new Act.
Ambiguity of "Express" Agreement: Although the bar for "express" is clearly intended to be high (requiring a specific, clear statement), the precise boundaries may yet be tested in court. Contract must avoid generic language and ensure their clause specifically states the governing law of the "arbitration agreement" or "arbitration clause" to override the statutory default.
Cross-border frictions: Where the seat is English but the transaction is anchored elsewhere, Section 6A’s default may lead to English law governing the arbitration clause even though the commercial relationship is controlled by another system—affecting non-signatory issues, separability, scope, assignment/novation and capacity questions determined under the clause’s proper law. Parties should assess whether they prefer those questions answered by seat law or by the contract’s governing law and draft accordingly. (This was the crux of several Kabab-Ji debates.)

Checklist: What to Do Now

If you are in-house counsel or a transactional lawyer:

Conduct a contract review and update any standard template arbitration clauses: rely on the seat-law default (do nothing) or add express wording to clarify which law governs the agreement.
Identify any contracts that may go into dispute since these changes – and assess whether Section 6A now has an impact on a contemplated dispute.

If you practice litigation:

Plead the seat’s law by default for clause-validity, scope, separability, non-signatory theories, and relief against court proceedings. Expect tribunals/courts to resist resurrecting Enka’s implied-choice arguments, except where the parties expressly opted out. 
Identify which contemplated or actual disputes are caught by Section 6A: For disputes brewing under legacy contracts, note that if proceedings are commenced on or after 1 August 2025, Section 6A will apply irrespective of when the contract was signed. This will change your governing law analysis.
Remember that English anti-suit injunctions are no longer automatic: Under Enka-era logic, you could sometimes invoke English law to get an anti-suit injunction even for foreign-seated arbitrations, because the arbitration agreement was “governed by English law by implication.” Now, unless the parties expressly choose English law for the arbitration clause, the default will be the foreign seat’s law, cutting off that route.
Stay alert: it will likely not be long until the first High Court and Court of Appeal cases interpreting Section 6A are heard. They will likely consider:
- What counts as an “express” choice;
- The boundary of the treaty/foreign-legislation carve-out;
- Whether Section 6A affects non-signatory extensions or novation cases.

Conclusion: Not A Dramatic Change, But Clear

Section 6A succeeds by being boringly clear. It nudges parties to be explicit when they truly want a non-seat clause law—and otherwise spares them the cost and risk of litigating implied-choice theories. For most commercial users, that is an immediate and material win.