The Loser-Pays Principle in Ontario: Understanding Your Costs Risk Before You Sue

Before you start a lawsuit in Ontario, there is a financial reality you must understand: the loser pays. Ontario courts follow the principle that the unsuccessful party generally pays a portion of the successful party's legal costs. That "portion" can amount to tens of thousands of dollars in a contested Superior Court matter.

The loser-pays rule is not unique to Ontario — it follows the English common-law tradition used across most Canadian provinces. But many people discover it only after they have already spent significant money on litigation, which is too late to make a fully informed decision about whether to sue.

What Does "Loser Pays" Actually Mean?

When a judge issues a final order at the end of a case, they almost always make a costs order alongside the substantive ruling. The default: the winning party is entitled to costs from the losing party.

Here is the practical reality:

• The loser pays, but not all of the winner's fees. Ontario courts award costs on a "partial indemnity" scale by default, which typically covers roughly 50% or less of the winner's actual legal bill. However, 50% of a large legal bill is still a large number.
• Costs accumulate throughout the proceeding. Costs can be awarded after individual motions during the litigation, not just at the end. Lose a motion, and you might be writing a cheque within weeks.
• Amount depends on complexity and conduct. A judge considers the complexity of the case, the amount at stake, and how each party conducted themselves. Obstructive or bad-faith behaviour can drive costs awards upward.

The Costs Exposure of Common Litigation Steps

To understand the risk, it helps to see where costs accumulate in a typical Superior Court matter:

Motions

Interlocutory motions (procedural applications during the lawsuit) routinely attract costs awards of a few thousand to tens of thousands of dollars, depending on length and complexity. A party who loses several motions can face compounding exposure long before trial.

Discovery Disputes

If you fail to produce documents you were required to disclose, or you behave unreasonably during examinations for discovery, the court can order costs against you — separate from the main proceeding.

Rejected Offers to Settle

This is the most significant costs amplifier. Under Rule 49 of the Rules of Civil Procedure, if a party makes a formal written offer to settle and the other side rejects it, and the trial result is no better than the offer, the rejecting party faces substantial indemnity costs for the period after the offer was made. Substantial indemnity is roughly 1.5 times the standard partial indemnity rate — a material step up.

Trial

If you go all the way to trial and lose, you face a costs award covering (at minimum) a portion of your opponent's preparation and trial time — often the most expensive phase of any litigation.

A Practical Example

Suppose you sue a contractor for $80,000 in shoddy work. The contractor's lawyer sends a formal offer six months in: settle for $40,000. You reject it. After a three-day trial, the judge awards you $35,000 — slightly less than the offer.

The result:

• You receive $35,000 from the contractor.
• But the contractor's lawyer submits a costs claim: partial indemnity to the date of the offer, substantial indemnity after it.
• The court awards the contractor $32,000 in costs (paid by you).
• Net result: you receive approximately $3,000 after paying the contractor's costs — and you still owe your own lawyer's bill.

This is not a hypothetical horror story. It is a realistic outcome in Ontario litigation when a reasonable offer is declined.

How to Manage Costs Risk

Understanding the risk does not mean avoiding litigation — it means approaching it strategically:

Assess the case honestly at the outset

Not every dispute is worth litigating. Get a candid legal opinion on your chances and your exposure before filing. A good litigator gives you the unflattering assessment, not just the encouraging one.

Take offers to settle seriously

Every settlement offer should be evaluated against the trial risk, the costs risk, and the time cost of continuing. Do not reject offers reflexively; analyze them against your realistic best-case outcome after accounting for your own legal fees.

Make your own Rule 49 offer early

If you are confident in your position, make a formal written offer under Rule 49 early in the litigation. This shifts the costs dynamic: if the other side rejects your offer and does not do better at trial, you are entitled to enhanced costs for the post-offer period.

Conduct yourself impeccably

Judges notice when parties are unreasonable, obstructive, or unnecessarily confrontational. Good conduct during litigation protects your costs position. Behave in court the way you would want a judge to see you.

Costs in Small Claims Court

Small Claims Court (for claims up to the monetary cap — verify the current limit at ServiceOntario) has a simplified costs regime. The costs awards are much more modest — typically a percentage of the amount claimed. The loser-pays principle still applies, but the financial stakes of a costs award are much lower than in the Superior Court.

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