STJ & Arbitration · Q1 2026
STJ & Arbitration
Q1 2026 Decisions — Key Rulings from Brazil’s Superior Court of Justice
Brazil’s Superior Court of Justice (STJ) has long been regarded as a pro-arbitration court — hence the nickname that circulates among practitioners: Friend of Arbitration. The first quarter of 2026 confirms that reputation, with an important nuance: the STJ does not merely uphold arbitration; it is also drawing its boundaries with increasing precision.
For this survey, we reviewed decisions published in the STJ’s official gazette (DJEN) between January 1 and March 31, 2026, and selected the rulings most relevant to parties that enter into or enforce contracts containing arbitration clauses.
The cases that follow are organized by topic. For each ruling, we set out the facts, the STJ’s decision, and the practical takeaway.
Authors: Adriano Dib | Antonio Marzão Barbuto Neto · Advocacia Adriano Dib, São Paulo, May 2026
Topics in this issue
— Validity and enforceability of arbitration clauses
— Scope and limits of arbitral jurisdiction
— Arbitral institution and constitution of the tribunal
— Arbitration and court enforcement proceedings
— Pre-arbitration interim relief
— Insurance and arbitration
— Validity and enforcement of arbitral awards
— International arbitration
Table of Contents
1Validity and Enforceability of Arbitration Clauses5 cases
2Scope and Limits of Arbitral Jurisdiction7 cases
3Arbitral Institution and Constitution of the Tribunal2 cases
4Arbitration and Court Enforcement Proceedings3 cases
5Pre-Arbitration Interim Relief1 case
6Insurance and Arbitration3 cases
7Validity and Enforcement of Arbitral Awards1 case
8International Arbitration1 case
⚠Open Divergence1 case
1
Section 1
Validity and Enforceability of Arbitration Clauses
Case 1
REsp 2.215.990/SP
STJ, 3rd Panel · 03/10/2026
Arbitrator bias
Facts
A party sought annulment of an arbitral award on grounds of bias. During the arbitration itself, the arbitrator had repeatedly been retained by the opposing party's law firm to issue legal opinions in unrelated matters — and had also provided personal legal services to one of the firm's partners. None of this was disclosed to the parties.
Ruling
Annulment upheld. The failure to disclose, combined with the depth of the economic ties with the opposing firm, objectively compromised the arbitrator's impartiality.
Practical Takeaway
Parties entering arbitration should actively investigate the background of arbitrators nominated by the other side. A biased arbitrator may cost not only the case, but years of subsequent litigation to set aside the award.
Case 2
AREsp 2.746.815/MT
STJ, 3rd Panel · 03/16/2026
Adhesion contracts
Facts
A franchisee sought to annul a franchise agreement in state court. The franchisor invoked the arbitration clause. The franchisee argued the clause was unenforceable because, as an adhesion contract, she had not specifically signed or initialed that clause.
Ruling
The STJ held that an arbitration clause in an adhesion contract is only effective if the adhering party specifically signs or initials it — or independently initiates arbitration. Since the lower court had not verified whether a specific signature or initial was present, the case was remanded for further analysis.
Practical Takeaway
Parties using adhesion contracts with arbitration clauses must ensure the counterparty specifically acknowledges that clause. Without this formal step, the clause may be set aside.
Case 3
REsp 2.159.956/PR
STJ, 3rd Panel · 02/10/2026
Electronic signature
Facts
A franchisee signed a franchise agreement electronically. The document contained an integrity code/hash on every page, but there was no specific electronic signature or initial on the arbitration clause itself.
Ruling
The arbitration clause was declared null. An electronic signature is valid, but the general signature on the contract — or the document's integrity code — does not substitute for a specific acceptance of the arbitration clause in an adhesion contract.
Practical Takeaway
Digital adhesion contracts require a specific electronic acceptance for the arbitration clause. The system must demonstrate that the adhering party expressly agreed to that clause, not merely to the contract as a whole.
Case 4
REsp 2.252.318/SP
STJ, 3rd Panel · 03/09/2026
Consumer contracts
Facts
A consumer signed an adhesion contract containing an arbitration clause and brought proceedings in state court. The company invoked the clause to dismiss the action.
Ruling
Appeal granted. In consumer adhesion contracts, the arbitration clause only prevails if the consumer agrees to arbitration at the time of the dispute. Filing the court action itself demonstrates the consumer's disagreement.
Practical Takeaway
Companies selling to consumers cannot rely on arbitration clauses to oust court jurisdiction. Arbitration requires the consumer's consent at the time of the dispute — not merely at the time of contracting.
Case 5
AREsp 1.840.722/GO
STJ, 4th Panel · 03/16/2026
90-day deadline
Facts
A party subject to enforcement of an arbitral award sought to challenge the validity of the clause and the award during enforcement proceedings, years after the arbitral judgment.
Ruling
Enforcement upheld. A party wishing to annul an arbitral award has 90 days to bring an annulment action — once that period lapses, the award's validity can no longer be challenged at the enforcement stage.
Practical Takeaway
Deadlines are absolute in arbitration. A party that receives an unfavorable arbitral award and fails to act within 90 days permanently loses the right to contest its validity.
2
Section 2
Scope and Limits of Arbitral Jurisdiction
Case 6
AgInt no AREsp 2.876.355/SP
STJ, 4th Panel · 03/23/2026
Evidence-gathering
Facts
A party attempted to obtain evidence through state court proceedings despite the existence of an arbitration clause. It argued the measure was urgent.
Ruling
Arbitral jurisdiction upheld. Urgency is the only exception permitting recourse to state courts before the tribunal is constituted — and it was not established in this case.
Practical Takeaway
An arbitration clause does not permit parties to use state court as a shortcut for evidence-gathering. Urgency must be concretely demonstrated.
Case 7
REsp 1.978.973/AP
STJ, 4th Panel · 03/09/2026
Trade note / protest
Facts
A company brought court proceedings to declare a trade note (duplicata) unenforceable and to annul its protest. The trade note arose from a contract containing an arbitration clause.
Ruling
Appeal not entertained. According to the STJ, determining whether the trade note had a valid underlying obligation requires examining the underlying contractual relationship; where an arbitration clause exists, that analysis belongs to the arbitrator, not the courts.
Practical Takeaway
Framing a dispute as a formal defect of the instrument is not enough. If the controversy depends on a contract containing an arbitration clause, the merits must be resolved in arbitration.
Case 8
REsp 1.993.564/RS
STJ, 3rd Panel · 03/16/2026
Tacit waiver
Facts
In a corporate dissolution dispute, a party participated in court proceedings without raising the arbitration clause. Only after an unfavorable outcome did it seek to invoke the clause.
Ruling
Too late. A party that engages in court proceedings without timely raising the arbitration clause tacitly waives its right to arbitration.
Practical Takeaway
Holding an arbitration clause does not guarantee arbitration. The clause must be raised at the outset of any court proceeding — failing to do so amounts to waiver.
Case 9
AREsp 2.645.003/MG
STJ, 4th Panel · 02/09/2026
Linked contracts
Facts
A company had a main contract containing an arbitration clause and separate loan agreements with a court jurisdiction clause. It sought to consolidate all disputes in arbitration, arguing the contracts were economically linked.
Ruling
Extension denied. Economic interdependence between contracts does not automatically carry an arbitration clause from one agreement to another.
Practical Takeaway
In transactions involving multiple contracts, each agreement must contain its own dispute resolution clause. Relying on automatic extension of an arbitration clause is a material risk.
Case 10
EDcl no REsp 2.048.065/SP
STJ, 4th Panel · 03/30/2026
Non-signatories
Facts
A party sought to compel early production of evidence against a third party that had not signed the arbitration clause.
Ruling
The STJ upheld state court jurisdiction over the non-signatory. Consent is the foundation of arbitral jurisdiction; an arbitrator cannot reach a party that did not sign the arbitration agreement, even if the evidence sought relates to the arbitral dispute.
Practical Takeaway
Arbitration does not automatically extend to third parties. Where a measure is directed against someone who did not sign the arbitration clause, recourse to state court may be necessary.
Case 11
AgInt no REsp 1.861.973/RS
STJ, 3rd Panel · 02/09/2026
Contribution claims
Facts
Two companies had an agency agreement containing an arbitration clause. One was held jointly liable in third-party litigation and brought a contribution claim against the other. The defendant invoked the arbitration clause.
Ruling
Clause inapplicable. The contribution claim arose from a court judgment — a legal fact extraneous to and arising after the agency agreement.
Practical Takeaway
An arbitration clause has objective limits: it covers disputes arising from the contract, not every dispute between the parties.
Case 12
AgInt no AREsp 2.995.453/PB
STJ, 4th Panel · 03/30/2026
Tax risk allocation
Facts
An energy trading company brought a claim to recover ICMS (state VAT) paid following tax assessments, alleging that the counterparty had misled it about a tax exemption. The energy supply contract contained an arbitration clause.
Ruling
Dispute referred to arbitration. The reimbursement obligation derived from the contractual allocation of tax risks — and therefore falls within the scope of the arbitration clause.
Practical Takeaway
Tax disputes may fall within arbitral jurisdiction if the reimbursement obligation finds its source in the contract.
3
Section 3
Arbitral Institution and Constitution of the Tribunal
Case 13
REsp 2.167.730/SP
STJ, 4th Panel · 03/09/2026
Closed institution
Facts
In eviction and rent collection proceedings, the lease agreement provided for arbitration before an institution that had since closed. The landlord attempted to proceed in state court, arguing it was impossible to use the originally chosen institution.
Ruling
Dismissal of court proceedings upheld. The closure of the chosen arbitral institution does not, by itself, invalidate the arbitration clause. Since the contract did not prohibit substitution of the arbitral body, the interested party should have followed the specific court procedure to constitute the arbitration.
Practical Takeaway
The closure of the named institution does not end arbitration. State courts may be engaged to facilitate the appointment process — but jurisdiction over the merits remains with the arbitrators.
Case 14
AgInt no AREsp 2.563.396/GO
STJ, 4th Panel · 02/09/2026
Service by notice
Facts
A party was served by public notice in arbitral proceedings after personal service attempts failed. The party later sought to annul the proceedings, arguing that service by notice is invalid in arbitration.
Ruling
Validity of service by notice upheld. The lower courts found that personal service had been genuinely attempted before resorting to public notice, and that a guardian ad litem had been appointed. Revisiting that finding would require re-examining the evidence.
Practical Takeaway
Evading service in arbitral proceedings is not a viable strategy. The proceedings may continue and the resulting award will stand.
4
Section 4
Arbitration and Court Enforcement Proceedings
Case 15
REsp 2.154.977/RJ
STJ, 4th Panel · 02/09/2026
Enforcement v. arbitration
Facts
A party sought to use pending arbitration proceedings to stay enforcement of an extrajudicial title in state court.
Ruling
Pending arbitration does not automatically stay enforcement of an extrajudicial title. A stay requires concrete and unequivocal evidence that the arbitration directly affects the validity of the title being enforced.
Practical Takeaway
Pending arbitration is not an automatic shield against court enforcement. The debtor must demonstrate specifically that the arbitration outcome could invalidate the title being enforced.
Case 16
AgInt no AREsp 2.943.223/GO
STJ, 3rd Panel · 03/02/2026
Merits of the title
Facts
A debtor invoked the arbitration clause in a motion to stay enforcement of an extrajudicial title.
Ruling
Enforcement is stayed only if the debtor's defense goes to the merits of the title. Defenses unrelated to the title's merits do not stay anything.
Practical Takeaway
There is a clear dividing line: merits-based defenses may stay enforcement; defenses unrelated to the title itself do not.
Case 17
EDcl no AREsp 2.128.758/SP
STJ, 4th Panel · 03/09/2026
Burden to initiate
Facts
A creditor was enforcing an extrajudicial title. The debtor invoked the arbitration clause and questioned who bears the burden of initiating arbitration to set aside the title.
Ruling
The burden is on the debtor. If it is the debtor who seeks to set aside the title, the debtor must initiate arbitration.
Practical Takeaway
A debtor wishing to contest a debt bears a dual burden: resisting enforcement in court and initiating arbitration. The creditor has no obligation to start arbitration.
5
Section 5
Pre-Arbitration Interim Relief
Case 18
REsp 2.191.178/MS
STJ, 4th Panel · 03/09/2026
Pre-arbitration relief
Facts
A party obtained interim relief from state court before arbitration was constituted. When arbitration was initiated, the question arose as to what happens to the court proceedings and who bears the legal costs.
Ruling
The court proceedings are extinguished once arbitration is constituted. However, the party that resisted the interim measure and forced the other to litigate bears the attorneys' fees, notwithstanding the technical dismissal.
Practical Takeaway
Seeking interim relief in court before arbitration is constituted is legitimate — but resisting it unjustifiably carries a cost. Once arbitration begins, control over interim measures passes to the tribunal.
6
Section 6
Insurance and Arbitration
Case 19
AREsp 2.515.588/SC
STJ, 4th Panel · 03/09/2026
Subrogation — general rule
Facts
An insurer paid a cargo claim arising from maritime transport and brought a subrogation action against the carrier. The carrier invoked the arbitration clause in the original shipping contract.
Ruling
The arbitration clause does not bind the subrogated insurer. Subrogation transfers the underlying credit, but not the procedural terms of the original contract.
Practical Takeaway
General rule: subrogated insurers are not bound by arbitration clauses in the original contracts. They may choose the forum for their recovery action.
Case 20
AgInt nos EDcl no REsp 2.092.246/SP
STJ, 4th Panel · 03/30/2026
Subrogation — prior knowledge
Facts
In a recovery action arising from cargo damage in international air transport, the subrogated insurer sought to litigate in Brazil. The carrier invoked the dispute resolution clause in the transport contract, arguing the insurer had prior knowledge of the relevant contract terms when issuing the policy.
Ruling
The clause was held enforceable against the insurer. Where the insurer had prior knowledge of the relevant terms of the guaranteed contract and integrated that risk into the policy, it may be bound by the agreed dispute resolution mechanism.
Practical Takeaway
The general rule of inenforceability against a subrogated insurer admits exceptions. If the insurer knew the relevant contract terms in advance and priced that risk accordingly, it may be required to observe the arbitration or jurisdiction clause.
Case 21
AgInt no AREsp 2.517.049/SP
STJ, 4th Panel · 03/30/2026
Performance bond
Facts
An insurer issued a performance bond over a contract containing an arbitration clause. The question arose whether the insurer was bound by the arbitration clause in the underlying contract.
Ruling
Yes. In a performance bond, the arbitration clause in the guaranteed contract extends to the insurer — the risk insured is the performance of the contract itself.
Practical Takeaway
A performance bond is different from cargo or liability insurance. An insurer issuing a performance bond over a contract with an arbitration clause is automatically subject to that clause.
7
Section 7
Validity and Enforcement of Arbitral Awards
Case 22
REsp 2.222.475/SP
STJ, 3rd Panel · 03/02/2026
Enforcement defenses
Facts
A party subject to an arbitral award sought to avoid enforcement by raising multiple defenses: absence of arbitral jurisdiction, nullity of the award, release of the guarantor due to the principal debtor's reorganization proceedings, and reduction of the penalty clause.
Ruling
All defenses rejected. The 90-day challenge period had lapsed; reorganization proceedings do not release a guarantor; and a penalty clause already reduced by the arbitral tribunal cannot be further reduced by state courts.
Practical Takeaway
A final arbitral award is meant to be enforced. Attempting to relitigate the merits at the enforcement stage — through untimely nullity claims, guarantor defenses or penalty clause arguments — has minimal prospects of success.
8
Section 8
International Arbitration
Case 23
HDE 1.607/UA
STJ, Full Court · 12/03/2025 (pub. 03/02/2026)
Foreign award recognition
Facts
A Ukrainian state-owned enterprise obtained an arbitral award against a Brazilian-Ukrainian joint venture that had been dissolved by federal legislation and succeeded by the Brazilian federal government (the Union), for USD 114,000.
Ruling
Recognition granted (10-2). The STJ's review in recognition proceedings is strictly formal. The Union's succession to the dissolved entity resulted from Brazilian legislation — not a foreign imposition. Disputes over the scope of the Union's liability are for enforcement proceedings.
Practical Takeaway
Recognition of a foreign arbitral award by the STJ is a formal proceeding. Arguments based on national sovereignty face an extremely high threshold: they require an absolute incompatibility with a foundational principle of Brazilian law.
⚠
Alert
Open Divergence
The case below was published in April 2026, after the close of the period covered by this issue. It is included because it reveals an open divergence between two panels of the STJ on a topic already addressed in this survey — whether a subrogated insurer is bound by the arbitration clause in the original contract. The matter is ripe for resolution by the Full Civil Panel (Segunda Seção).
Case 24
REsp 2.106.052/RJ
STJ, 3rd Panel · 04/13/2026
Split between panels
Facts
The same carrier that had prevailed in AREsp 2.515.588/SC (Q1 2026) by excluding the subrogated insurer from arbitration was defeated on analogous facts two months later before a different panel. The insurer brought a recovery action in state court and the carrier again invoked the arbitration clause in the transport contract.
Ruling
The arbitration clause binds the subrogated insurer. Subrogation transfers all rights and actions of the insured — including the arbitration agreement, which the court characterized as accessory to the credit rather than a standalone procedural arrangement.
Practical Takeaway
This issue is unsettled at the STJ. The 3rd and 4th Panels reached opposite conclusions on the same question involving the same party. Until the Full Civil Panel (Segunda Seção) resolves the divergence, insurers and carriers face material legal uncertainty.