An arbitration is heard by either one arbitrator or a panel of three. Under the Federal Arbitration Act, the default when the parties’ agreement is silent on how many arbitrators are in an arbitration is a single arbitrator.1Office of the Law Revision Counsel. 9 U.S. Code 5 – Appointment of Arbitrators or Umpire Which number you end up with depends on what your contract says, the rules of the institution administering the case, the dollar amount in dispute, and how complex the matter is.
One Arbitrator or Three
A sole arbitrator handles most domestic commercial arbitrations. One person reviews the evidence, runs the hearing, and issues the award. Scheduling is faster because you’re coordinating one calendar. Fees are lower because you’re paying one professional, not three.
A three-arbitrator panel is reserved for larger or more complicated disputes. Each arbitrator brings a different background, three perspectives reduce the chance that one blind spot drives the outcome, and deliberation among the panel can produce a more carefully reasoned decision. The cost is real. A panel roughly triples arbitrator compensation, adds scheduling friction, and can stretch the timeline by weeks or months. When accuracy and thoroughness matter more than speed and price, parties accept that tradeoff.
Why Panels Use Odd Numbers
You will almost never see a two-arbitrator panel. Even numbers invite deadlock, and there is no built-in way to break a tie between two decision-makers. Odd-numbered panels guarantee that a majority can form. That is why every major arbitration framework defaults to one or three, and why a contract that accidentally calls for two arbitrators is often read to require a third presiding arbitrator or umpire. If you are drafting an arbitration clause, pick one or three.
What the Administering Institution Says
Your arbitration clause probably names an institution to administer the case. Each one has its own default, and the defaults differ more than people expect.
AAA Commercial Rules
The American Arbitration Association defaults to a single arbitrator for commercial disputes. Under Rule R-17, if your agreement does not specify a number, the case goes to one arbitrator unless the AAA decides the situation calls for three. Either party can request a three-person panel in its initial filing, and the AAA will weigh that request.2American Arbitration Association. Commercial Arbitration Rules and Mediation Procedures
Construction disputes run under a separate AAA ruleset with a dollar trigger. Claims exceeding $3 million automatically go to a three-arbitrator panel unless the parties agree otherwise.3American Arbitration Association. 2024 Construction Industry Arbitration Rules and Mediation Procedures
JAMS
JAMS defaults to one arbitrator across the board. Rule 7 of its Comprehensive Arbitration Rules sends all cases to a single neutral unless every party agrees otherwise. JAMS does not use a dollar threshold to trigger a panel.4JAMS. Comprehensive Arbitration Rules and Procedures If the parties do agree to three, Rule 7 requires them to designate a chairperson or let JAMS pick one.
FINRA
Securities disputes administered by FINRA follow a tiered system based on the amount at stake:
- $50,000 or less: one arbitrator, using simplified procedures.
- $50,001 to $100,000: one arbitrator, unless both parties agree in writing to three.
- Over $100,000: three arbitrators, unless both parties agree in writing to one.
Claims with unspecified amounts or those not seeking money damages also go to a three-arbitrator panel by default.5FINRA. FINRA Rule 12401 – Number of Arbitrators FINRA ties panel size directly to dollar thresholds more clearly than any other major U.S. forum.
ICC
The International Chamber of Commerce defaults to a sole arbitrator for international commercial disputes. If the ICC Court determines a case is complex enough to warrant three, it directs a panel instead. The ICC rules name no specific dollar figure; the Court decides based on the nature and scope of the dispute.6International Chamber of Commerce. ICC Arbitration Rules 2021 – Article 12
International Default Under UNCITRAL
The pattern flips in international arbitration. The UNCITRAL Model Law, which forms the basis for arbitration statutes in dozens of countries, defaults to three arbitrators when the parties have not agreed on a number. That is the opposite of U.S. domestic practice, where the Federal Arbitration Act and most institutional rules default to one. If your dispute involves parties in different countries, check which arbitration law governs before assuming a sole arbitrator.
What Drives the Choice When the Agreement Is Silent
The parties get the first and strongest say. You can specify the number of arbitrators directly in the clause you sign, and that choice overrides any institutional default. Party autonomy is baked into every major arbitration framework and into the Federal Arbitration Act itself.1Office of the Law Revision Counsel. 9 U.S. Code 5 – Appointment of Arbitrators or Umpire
When the agreement does not pick a number, three factors tend to push the decision. Complexity matters most. A straightforward breach-of-contract case worth $200,000 does not need three arbitrators deliberating, but a multi-party construction dispute involving technical engineering questions probably does. Financial stakes also play a role, since higher-value disputes justify the added cost of a panel and benefit from the additional scrutiny. Cost pulls the other way. A three-arbitrator panel can cost roughly three times as much in arbitrator fees alone, before you add longer hearings and harder scheduling. Parties in smaller disputes sometimes agree to a sole arbitrator even when institutional rules would give them a panel, because the panel’s cost would eat into what is actually at stake.
How the Arbitrators Get Picked
Selection depends on whether you are naming one arbitrator or building a panel.
A Sole Arbitrator
The simplest path is mutual agreement. Both sides identify someone they trust, and that person accepts the appointment. When the parties cannot agree, most institutions run a list-based process. JAMS sends both parties a list of at least five candidates with background descriptions. Each side strikes two names and ranks the rest in order of preference. The candidate with the highest combined ranking is appointed.7JAMS. Comprehensive Arbitration Rules and Procedures – Rule 15 The AAA follows a similar strike-and-rank approach, with list sizes of five, ten, or fifteen candidates depending on the case.
If the list process fails because of strikes, conflicts, or availability, the institution appoints an arbitrator from its roster. If no institution is involved at all, the Federal Arbitration Act lets either party ask a court to make the appointment.1Office of the Law Revision Counsel. 9 U.S. Code 5 – Appointment of Arbitrators or Umpire
A Three-Arbitrator Panel
The most common method in U.S. commercial arbitration gives each side one pick. You select your arbitrator, the other party selects theirs, and those two arbitrators jointly choose the third, who serves as the presiding arbitrator or chair.8JAMS. Comprehensive Arbitration Rules and Procedures – Rule 7 The chair breaks ties and typically runs procedural decisions during the hearing.
One widespread misconception is worth clearing up. The two party-selected arbitrators are not advocates for the side that picked them. Under JAMS rules, all three arbitrators must be neutral and independent of the appointing party unless the parties specifically agree otherwise. The AAA’s commercial rules follow the same principle. Your party-appointed arbitrator is a neutral decision-maker who happened to be selected by you.
When the two party-appointed arbitrators cannot agree on a chair, the administering institution steps in. Some appoint the third arbitrator directly, others run a separate list-and-rank process just for the chair. Where no institution is involved, a court can fill the vacancy.