Arbitration In 2026: Section 15, Substitution Of Arbitrators And The Supreme Court’s Evolving Limits On Judicial Interference

1. Introduction

Recent 2026 Supreme Court judgments have pushed Section 15 of the Arbitration and Conciliation Act, 1996 to the center of arbitration practice. The Court has clarified that when an arbitrator's mandate terminates, and a substitute is appointed courts have very limited powers because they must facilitate substitution without rewriting past proceedings or nullifying them or allowing judicial control over the arbitral process to expand. The rulings establish boundaries which determine when parties and their counsel and institutions can request tribunal changes and establish limitations on judicial authority during arbitrator substitutions and mandate that the ongoing proceedings must be maintained.

This article explains the statutory framework of Section 15 through the Supreme Court decisions from 2025 to 2026 and shows how these decisions will affect the process of creating legal clauses and conducting arbitration hearings and handling substitution requests.

2. How Does Section 15 Actually Work?

Statutory design

Section 15 sits alongside Sections 13 and 14 and deals with termination of mandate and substitution of arbitrators. In essence:

1. Section 15(1) provides that, in addition to grounds under Sections 13 (challenge) and 14 (failure or impossibility to act), an arbitrator’s mandate terminates where (a) the arbitrator withdraws from office for any reason, or (b) the parties agree to terminate the mandate.
2. Section 15(2) then states that, where the mandate terminates, “a substitute arbitrator shall be appointed according to the rules that were applicable to the appointment of the arbitrator being replaced.”

The provision is deliberately narrow as it focuses on how to fill the vacancy, not on reopening or reviewing what has already occurred before the earlier tribunal.

Interface with Sections 11, 14, 16, 17 and 37

In practice, substitution issues interact with other parts of the Act:

Section 11: court or institution’s power to appoint arbitrators where parties fail to do so.

Section 14: termination of mandate where an arbitrator becomes de jure or de facto unable to perform functions or fails to act without undue delay.

Section 16: tribunal’s competence to rule on its own jurisdiction.

Section 17: tribunal’s power to grant interim measures.

Section 37: limited appeals against certain orders, including some Section 17 orders.

The recent interventions of the Supreme Court through its recent rulings have made clear that Section 15 should not be used as the backdoor of exercising appeal or supervisory jurisdiction over the matters under Sections 16,17 or 37.

3. Courts Cannot Nullify Past Proceedings Under Section 15(2)

The core ruling

In early 2026, the Supreme Court considered a case where a High Court, while appointing a substitute arbitrator under Section 15(2), went further and declared multiple earlier sittings and orders of the original tribunal a nullity on the ground that they had been conducted during an Insolvency Code moratorium. The Supreme Court held that the High Court had exceeded its jurisdiction. Section 15(2) gave it only the power to ensure appointment of a substitute in accordance with the original procedure, not to invalidate prior arbitral proceedings or orders.

The Court stressed that the Arbitration Act is a self-contained code with carefully demarcated avenues and limits for court intervention. By using a Section 15(2) application to:

1. overturn a prior order rejecting a Section 16 jurisdictional objection (which is not immediately appealable),
2. disturb Section 17 interim orders (which have their own appeal mechanism under Section 37), and
3. render other procedural orders void,

the High Court had effectively exercised powers not conferred by the statute.

Continuity of proceedings and protection of third party rights

The Supreme Court has emphasized that parties need to maintain existing arbitration processes until they reach a different agreement about proceeding. Existing hearings and orders maintain their full legal effect while the new arbitrator continues from the current case progress. The Court observed that cancelling previous judicial proceedings would create unfair situations which would harm both parties and third parties who obtained rights through provisional orders, including directions about security and payments.

This approach is consistent with earlier analyses which read Section 15(2) as a mechanism to fill a vacancy while preserving the efficacy and finality of the arbitral process.

When Must A Replacement Be Appointed?

The Supreme Court in a related decision clarified that parties involved in arbitration must assess their specific situation and applicable regulations before deciding whether to replace an arbitrator after a tribunal loses its authority to operate. The Court explained that:

1. Section 15(1) scenarios such as withdrawal by the arbitrator or consensual termination usually trigger Section 15(2), requiring a substitute to be appointed following the original procedure, unless the parties agree to a different course (including dropping the reference).
2. Where the entire tribunal’s mandate has come to an end for reasons covered by other provisions or by institutional rules, parties may need to invoke fresh appointment mechanisms (for example under institutional rules or Section 11), and a mechanical reading of Section 15 may not apply.

In short, the Court cautioned against treating Section 15 as a blanket rule for every situation where an arbitrator or tribunal is no longer in office. Context and the parties’ agreement continue to matter.

Judicial Intervention Beyond Section 15

The debate on Section 15 is part of a wider conversation about the outer limits of judicial intervention in Indian arbitration. Commentators have pointed to decisions such as Gayatri Balasamy v. ISG Novasoft Technologies where the Supreme Court used its powers to modify an arbitral award rather than merely set it aside. This shows of a trend towards greater judicial willingness to correct perceived injustice, even at the cost of textual minimal interference ideals. Scholars argue that such moves can create uncertainty for parties who chose arbitration expecting finality and a narrow review window.

In this context, the 2026 Section 15, line of cases serves as a judicial correction which establishes that courts do not possess authority to handle every single procedural or substantive issue because there exists no legal power which allows them to do so.

4. Practical Implications For Arbitration Clauses And Institutions

Drafting appointment and substitution mechanisms

The decisions demonstrate to in-house teams and transactional lawyers that they need to draft their appointment and substitution clauses with greater attention to detail. The following points require examination:

1. Providing a clear fallback mechanism for substitution (for example, designating an institution or a specified authority) that will apply when an arbitrator withdraws or is unable to act.
2. Ensuring that the substitution mechanism mirrors the original appointment logic, consistent with Section 15(2), to minimise disputes.
3. For multi member tribunals, clarifying whether proceedings can continue with remaining arbitrators in certain scenarios and how a replacement is to be appointed.

Well structured clauses reduce the scope for Section 11 or Section 15 litigation and make it easier for courts to confine themselves to a narrow appointment role.

Institutional rules and continuity

Arbitral institutions should ensure that their rules and practice notes:

1. The appointment of a substitute arbitrator should maintain all existing orders and directives which remain in effect until both parties reach an agreement or the tribunal decides which specific procedures should be repeated to ensure equitable treatment.
2. The extent to which substitute arbitrators can change existing procedural directives that include scheduling and evidence cut-off times without breaking process continuity needs clarification.
3. The handover process requires standard protocols which include record transfer and summary delivery of previous orders and status updates to ensure that replacement personnel can begin their duties without delays.

Institutional provisions aligned with the Supreme Court’s reading of Section 15 can reduce the temptation for parties to invite courts to “reset” proceedings.

5. Strategy For Parties Seeking Or Resisting Substitution

When seeking substitution

Parties moving under Section 15(2) (often before a High Court when the parties’ mechanism fails) should:

1. Frame relief narrowly. Confine the prayer to appointment of a substitute arbitrator following the original procedure or a court approved mechanism.
2. Avoid seeking to invalidate past hearings or orders, or to revisit Section 16/17 issues such requests are unlikely to succeed and may be viewed as an abuse of the limited Section 15 jurisdiction.
3. Where fairness genuinely requires repeating certain steps (for example, because a key witness was heard only by the departed arbitrator), explain why the tribunal and not the court should manage this within its procedural discretion once reconstituted.

When resisting overbroad court interventions

Respondents resisting expansive orders under Section 15 can rely on the 2026 Supreme Court pronouncements to argue that:

1. The High Court’s role is confined to appointment, not supervision, of the substitute tribunal.
2. Any attempt to nullify prior proceedings or to disturb Section 16/17 orders is ultra vires Section 15 and cuts across the appeal structure of Section 37.
3. The principle of competence and arbitral autonomy would be undermined if substitution proceedings became a vehicle for indirectly appealing non appealable orders.

Courts are likely to be receptive to these arguments given the Supreme Court’s explicit reaffirmation of limited, codified intervention.

6. Key Takeaways For Arbitration Users In 2026

The 2026 Section 15 jurisprudence establishes three essential guidelines which arbitration users must follow.

1. Substitution is about continuity, not a reset. The Section 15(2) provision permits replacement of an arbitrator, but it does not permit courts to erase all previous judicial proceedings and decisions which remain in effect.
2. Judicial powers remain bounded by the Act. High Courts cannot use substitution proceedings to revisit jurisdictional or interim issues governed by Sections 16, 17 and 37, or to exercise broad supervisory powers absent statutory basis.
3. The process of drafting documents and designing institutions needs to be executed with proper standards of quality. Clear appointment and substitution clauses together with institutional rules which maintain continuity, enables parties to control their legal processes, while their operational activities remain in accordance with the Supreme Court's requirement for arbitrators' independent decision making.

For counsel and in house teams, understanding these limits is critical both when structuring arbitration agreements and when reacting to tribunal changes mid proceeding.

The content of this article is intended to provide a general guide to the subject matter. Specialist advice should be sought about your specific circumstances.