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Mediator vs. Arbitrator in Ontario: What’s the Difference in Their Role?

The real difference between a mediator and an arbitrator in Ontario — what each one does, how much power they have, and which one you actually need.

Litigation5 min readTSLBy the Treadstone Law team · OntarioUpdated 2026-07
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Key takeaways
  • A mediator helps you reach your own agreement.
  • A mediator’s entire job is to help two, or more, parties find their own resolution.

People often use "mediator" and "arbitrator" interchangeably, but the two roles are fundamentally different, not just in name, but in how much power each person actually has over the outcome of your dispute. Understanding the difference between a mediator and an arbitrator in Ontario matters before you agree to either process, because you’re giving up a different amount of control depending on which one you choose.

The Core Difference in One Line

A mediator helps you reach your own agreement. An arbitrator decides the outcome for you.

That single distinction shapes everything else about how each process works.

Side-by-Side Comparison

MediatorArbitrator
Decision-making powerNone — cannot impose an outcomeFull — issues a binding decision, the award
Role in the sessionFacilitates discussion, helps identify common groundHears evidence and arguments, then decides
Outcome if the process doesn’t produce a resultNo settlement — the dispute continues elsewhereAlways produces a binding award, once the hearing concludes
ConfidentialityDiscussions are generally confidentialThe hearing is a formal, private proceeding rather than confidential settlement talk
Governing frameworkLargely contractual, with no dedicated Ontario statute governing private mediation itselfGoverned by Ontario’s Arbitration Act, 1991
Enforceability of outcomeA settlement becomes binding only once both sides sign an agreementThe award is generally enforceable much like a court judgment, with limited appeal rights
Formality of processInformal, conversational, flexibleMore formal — resembles a private trial, with evidence and submissions

What a Mediator Actually Does

A mediator’s entire job is to help two, or more, parties find their own resolution. This can involve:

At no point does a mediator have authority to force either side to accept anything. If neither side agrees, mediation simply ends without a binding outcome.

What an Arbitrator Actually Does

An arbitrator functions much more like a private judge:

Because an arbitrator’s decision is imposed rather than agreed to, the process resembles a private trial more than a negotiation.

Which One Do You Need?

How Each One Is Typically Chosen

A mediator is usually selected by mutual agreement between the parties, or drawn from an approved roster where a court process requires mediation. Because a mediator never imposes a decision, the parties have wide latitude to pick someone whose style and background they’re both comfortable with.

An arbitrator’s selection is more consequential, since that person will ultimately decide the outcome. Parties often specify in advance, within an arbitration clause or a separate arbitration agreement, how the arbitrator will be appointed — for example, by mutual agreement, by each side naming one arbitrator who then jointly select a third, or through a process set out in the Arbitration Act, 1991 if the parties can’t agree. Taking the appointment process seriously matters more for an arbitrator than a mediator, precisely because you can’t simply reject their conclusion once it’s made.

Frequently asked questions

Can the same person be both my mediator and my arbitrator?

Yes, in a med-arb process the same neutral sometimes fills both roles in sequence, mediating first and then arbitrating if needed. Some parties prefer a different person for each role to keep the two functions clearly separate.

Is an arbitrator’s decision final?

Generally yes, subject to only limited grounds of appeal, which is one of the main tradeoffs of choosing arbitration over litigation. The exact appeal rights depend on the parties’ arbitration agreement and the Arbitration Act, 1991.

Do I have to accept whatever a mediator suggests?

No. A mediator can propose ideas and settlement structures, but you are never obligated to accept them. You only become bound once you actually agree to and sign a settlement.

Which is more expensive, mediation or arbitration?

Arbitration is generally more involved and typically more expensive than mediation, since it resembles a formal hearing with evidence and legal argument, while mediation is usually a shorter, more informal process. Exact costs vary widely by dispute.

This article is general information, not legal advice. Reading it does not create a lawyer-client relationship. Ontario laws, tax rates, and government programs change, and how the law applies depends on your specific facts. For advice about your situation, speak with a licensed Ontario lawyer. Treadstone Law is licensed by the Law Society of Ontario — reach us at 1-844-900-1070 or start a file online.

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