1. What Is Consolidation of Arbitration Cases
Consolidation is the process of combining two or more separate arbitrations into a single proceeding. After consolidation, the disputes are heard together by one tribunal, and the tribunal issues a single award resolving all the consolidated claims.
Consolidation is distinct from:
- Joinder, which adds a party to an existing arbitration
- Multiple contracts arbitration, which allows claims under several contracts to be brought in one arbitration from the outset
Consolidation results in a single arbitration. The original arbitrations cease to exist as separate proceedings.
For more on Joinder and Multiple Contracts arbitration, refer to the links to articles on each of them above.
2. Reasons for Parties to Seek Consolidation
Consolidation offers several advantages:
Efficiency
Hearing related disputes together avoids duplication of procedural steps, evidence, and submissions. One tribunal, one hearing, one award
Cost Savings
Consolidated proceedings reduce arbitrator fees, institutional fees, and legal costs compared to running multiple parallel arbitrations.
Consistency
Separate tribunals deciding related disputes may reach inconsistent findings on the same facts. Consolidation eliminates this risk by placing all issues before one decision-maker.
Avoiding tactical fragmentation
Without consolidation, a party may face multiple proceedings on the same project or transaction, each requiring separate attention and resources. Consolidation prevents disputes from being artificially split across forums.
However, consolidation is not always appropriate. It may delay proceedings that are already advanced, introduce additional complexity, or raise confidentiality concerns where different parties are involved in different arbitrations.
3. When Consolidation Is Available Under the SIAC Rules
Rule 8 of the SIAC Rules 2025 (7th Edition) governs consolidation. The Court of Arbitration may consolidate two or more arbitrations where:
a. All parties agree to consolidation; or
b. All the claims are made under the same arbitration agreement; or
c. The claims are made under more than one arbitration agreement, and:
- The arbitrations are between the same parties
- The disputes arise out of the same legal relationship
- The Court finds the arbitration agreements to be compatible
d. The claims are made under more than one arbitration agreement, and:
- The arbitrations involve a common question of law or fact
- The disputes arise out of the same transaction or series of transactions
- The Court finds the arbitration agreements to be compatible
| Ground | Requirements |
| All parties agree | Consent of all parties to all arbitrations |
| Same arbitration agreement | All claims arise under one arbitration agreement |
| Same parties, same legal relationship | Same parties + same legal relationship + compatible agreements |
| Common questions, same transaction | Common question of law or fact + same transaction or series of transactions + compatible agreements |
What “compatible” means
The Court of Arbitration must find that the arbitration agreements are “compatible” before ordering consolidation under grounds (c) or (d). Compatibility typically requires:
- The same arbitral institution (e.g. SIAC)
- The same or compatible procedural rules (e.g. SIAC Rules 2025)
- The same seat (or seats that do not conflict) (e.g. Singapore)
- No provisions that would make consolidation impossible (e.g., confidentiality carve-outs, different tribunal appointment mechanisms that cannot be reconciled)
Minor differences in clause wording do not necessarily make agreements incompatible, but significant divergences may.
4. The Consolidation Process
Who decides
Applications for consolidation are decided by the SIAC Court of Arbitration, not by the tribunal. This reflects the institutional nature of the decision: consolidation affects the structure of proceedings, tribunal composition, and administrative arrangements.
Timing
An application for consolidation may be made at any time, but timing affects the practicality of consolidation:
- Early applications (before tribunals are constituted in either arbitration) are easier to accommodate. The SIAC can appoint a single tribunal for the consolidated proceeding.
- Later applications (after tribunals are constituted) raise questions about which tribunal will hear the consolidated case and what happens to work already done in the separate proceedings which may have 2 or more tribunals already constituted.
Procedure
A party seeking consolidation submits a Request for Consolidation to SIAC, identifying the arbitrations to be consolidated and the grounds relied upon. SIAC notifies all parties and invites responses. The SIAC Court of Arbitration then decides whether to consolidate.
The SIAC Court of Arbitration’s decision is administrative, not a ruling on the merits. It does not bind the tribunal on jurisdictional questions that may arise in the consolidated proceeding.
5. Steps to Consolidate Arbitrations
Step 1: Identify the grounds
Review the arbitration agreements in each proceeding and assess which ground under Rule 8 applies:
- Is there agreement from all parties? If so, consolidation is straightforward.
- Are the claims under the same arbitration agreement? If so, consolidation is available without needing to show compatibility.
- Are the agreements compatible? If the arbitrations arise under different agreements, you will need to demonstrate compatibility and either (i) same parties and same legal relationship, or (ii) common questions and same transaction.
Step 2: Consider timing
Consolidation is easiest before tribunals are constituted. If one or both arbitrations are well advanced, consider whether consolidation will cause delay and whether the efficiency gains justify any disruption.
Step 3: Prepare the application
A Request for Consolidation should include:
- Identification of the arbitrations to be consolidated (case numbers, parties, arbitration agreements)
- The ground(s) for consolidation under Rule 8
- An explanation of why consolidation is appropriate (common issues, same transaction, efficiency gains)
- If compatibility is in issue, an analysis of why the arbitration agreements are compatible
- Any proposal regarding tribunal composition for the consolidated proceeding
Step 4: Submit to SIAC
Submit the Request for Consolidation to SIAC. SIAC will notify all parties to all affected arbitrations and set a timetable for responses.
6. If You Are Opposing Consolidation
Consolidation is not automatic, and there are legitimate reasons to oppose it.
Common grounds for opposition
- The arbitration agreements are not compatible (e.g., different seats, different procedural rules, different confidentiality provisions)
- The disputes do not arise from the same transaction or series of transactions
- There is no common question of law or fact
- Consolidation would cause prejudice (e.g., delay to a proceeding that is near completion)
- Confidentiality concerns (e.g., one arbitration involves sensitive information that should not be shared with parties in the other arbitration)
- Different parties have different interests that would be better served by separate proceedings
Procedure for opposition
If you receive notice of a consolidation application, you will have an opportunity to respond. Your response should address:
- Why the grounds for consolidation are not met
- Any prejudice that would result from consolidation
- If relevant, an alternative proposal (e.g., coordinated proceedings rather than full consolidation)
Consider the probability of a successful contest
Opposing consolidation is not without cost. If the Court orders consolidation over your objection, you will need to participate in the consolidated proceeding. Consider whether opposition is likely to succeed and whether the resources spent opposing consolidation are justified.
7. SIAC’s Consolidation Decision Cannot be Appealed to the Courts
If SIAC decides to consolidate (or refuses to consolidate), that decision is final during the arbitration. The Singapore courts will not step in to review it.
This was confirmed by the Singapore Court of Appeal in DMZ v DNA [2025] SGCA 52. In that case, A party was unhappy with a procedural decision made by the SIAC Registrar. It went to the Singapore High Court asking the court to overturn the Registrar’s decision. The High Court said it had no power to do so. The party appealed. The Court of Appeal agreed: the courts cannot review SIAC’s procedural decisions.
Why the courts will not intervene
Singapore law is designed to let arbitrations run without court interference. The International Arbitration Act and the UNCITRAL Model Law (which applies in Singapore) say that courts can only get involved in specific situations — and reviewing SIAC’s administrative decisions is not one of them.
The SIAC Rules themselves (Rule 40.2) also say that parties cannot challenge decisions made by the Registrar or the Court of Arbitration in court, except in limited circumstances (like challenges to arbitrators).
What this means if you disagree with a consolidation decision
If SIAC grants consolidation and you opposed it, or if SIAC refuses consolidation and you wanted it, you cannot go to court to have that decision reversed.
Your only option is to continue with the arbitration and raise the issue later, after the award is issued. At that stage, you could argue (for example) that the consolidation caused a breach of natural justice that affected the outcome. But this is a high bar, and such challenges rarely succeed.
The practical takeaway
Make your best case at the consolidation application stage. Present all your arguments and evidence to the SIAC Court of Arbitration. Once the decision is made, you will have to live with it for the duration of the arbitration.
8. What Happens After Consolidation Is Ordered
Once the Court of Arbitration orders consolidation, the separate arbitrations are merged into a single proceeding. Several practical questions arise:
Tribunal composition
If no tribunal has been constituted in any of the arbitrations, SIAC will proceed to constitute a single tribunal for the consolidated case.
If tribunals have been constituted, the Court determines which tribunal will hear the consolidated proceeding. The Court may:
- Appoint one of the existing tribunals to continue
- Appoint a new tribunal
- Invite parties to agree on tribunal composition
Procedural timetable
The tribunal in the consolidated proceeding will issue a new procedural timetable, taking into account submissions and evidence already filed in the separate arbitrations. Parties may need to update or supplement their submissions to address all consolidated claims.
Treatment of prior work
Work done in the separate arbitrations (submissions, document production, witness statements) is generally preserved. The tribunal will determine how to integrate this material into the consolidated proceeding.
Single award
The tribunal will issue a single award resolving all claims in the consolidated proceeding. The award is binding on all parties.
9. Consolidation vs Joinder vs Multiple Contracts
These mechanisms serve related but distinct purposes:
| Mechanism | What It Does | When to Use | Result |
| Consolidation (Rule 8) | Combines separate arbitrations into one | When related arbitrations are pending and should be heard together | One arbitration, one award |
| Joinder (Rule 7) | Adds a party to an existing arbitration | When a non-party should be included in an ongoing arbitration | Additional party joined to existing arbitration |
| Multiple Contracts (Rule 6) | Allows claims under multiple contracts to be commenced in one arbitration | When disputes arise under related contracts at the outset | One arbitration from the start |
Consolidation is about combining proceedings. Joinder is about adding parties. Multiple contracts is about structuring a single arbitration to cover multiple agreements.
A party facing related disputes may use more than one mechanism. For example, a party may commence an arbitration under multiple contracts, then later apply to consolidate that arbitration with another pending proceeding.
10. Drafting Considerations
The ease of consolidation depends significantly on how the arbitration agreements are drafted.
Facilitating consolidation
If a transaction involves multiple agreements and the parties anticipate that disputes may need to be resolved together:
- Use identical arbitration clauses in all related agreements
- Specify the same seat, institution, and procedural rules
- Include an express provision permitting consolidation
- Avoid confidentiality provisions that would preclude information sharing between related arbitrations
Restricting consolidation
If a party wishes to limit the risk of consolidation:
- Include a provision expressly excluding consolidation
- Use different arbitration clauses in different agreements (though this creates other complexities)
- Include strict confidentiality provisions that would make consolidation impractical
Note that parties cannot unilaterally prevent consolidation if the institutional rules permit it. The drafting can make consolidation more difficult, but the ultimate decision rests with the Court of Arbitration applying the rules.
Conclusion
Consolidation under the SIAC Rules allows related arbitrations to be combined into a single proceeding, promoting efficiency, reducing costs, and avoiding inconsistent outcomes. The mechanism is available where parties agree, where claims arise under the same arbitration agreement, or where compatible agreements and common issues justify combining the disputes.
For parties seeking consolidation, the key is demonstrating that the grounds under Rule 8 are met and that consolidation serves the efficient resolution of the disputes. For parties opposing consolidation, the focus is on incompatibility, prejudice, or the absence of common issues.