Cost Consequences of Mixed Success in Ontario Civil Litigation

Trials rarely end in a clean sweep for one side. More often, a plaintiff wins on some claims and loses on others, or a defendant successfully fends off the main claim but loses on a counterclaim. When that happens, the usual "loser pays" assumption about legal costs stops being straightforward — this is what Ontario courts call mixed success, and it changes how costs get decided.

Understanding how courts typically approach divided outcomes can help you set realistic expectations about what a partial win — or a partial loss — is actually going to cost you.

The General Rule: Costs Follow the Event — But Not Always

Under the Courts of Justice Act, Ontario courts have broad discretion over legal costs, and the general starting point is that an unsuccessful party contributes to the successful party's costs, typically assessed on the partial indemnity scale. But that "general rule" assumes a clear winner and loser. Once success is divided across different claims or issues, the court has to decide what "the event" actually was — and that's where mixed success comes in.

What "Mixed Success" Looks Like

Mixed success can arise in several common patterns:

• A plaintiff sues on several distinct claims and wins some, loses others
• A defendant successfully defeats the main claim but loses on a counterclaim they brought
• A plaintiff wins the case overall but recovers significantly less than what they claimed
• Multiple parties each achieve partial success against each other in a multi-party dispute

In all of these situations, treating one side as the simple "winner" for costs purposes would misrepresent what actually happened at trial.

How Courts Typically Respond

Ontario courts have several tools available when success is divided, and which one applies depends heavily on the specific facts:

• No costs to either party — recognizing that both sides had some success and some failure
• Apportioned costs by issue — costs awarded (in each direction) based on which side succeeded on which distinct issue
• Partial costs to the party with greater overall success — often reduced from what a full "winner" would receive, to reflect the mixed outcome
• Each party bears their own costs — a related but distinct outcome from "no costs," sometimes used when both sides had substantial, roughly comparable success

There's no fixed formula that applies automatically — a court exercises its discretion under Rule 57, weighing the overall picture of the case.

Factors Courts Weigh

• The overall result, not just a claim-by-claim tally — courts look at who substantially succeeded when the dust settles
• Whether a party's litigation positions were reasonable, including whether time was spent on issues that turned out to be unnecessary or unsuccessful
• Formal settlement offers, since a party who did better at trial than an offer they rejected (or an offer they made that wasn't accepted) can affect the costs outcome
• The parties' conduct during the litigation, including whether the process was needlessly prolonged or complicated
• The proportion of the case devoted to the issues each side won or lost on

Practical Takeaways for Litigants

1. Don't assume a partial win means a full costs recovery. Even a favourable result on your main claim can come with a reduced costs award if you lost on other issues along the way.
2. Think carefully about which claims to pursue. Adding weak or peripheral claims can drag down your overall costs position even if your core claim succeeds.
3. Formal settlement offers matter. A reasonable offer made early can meaningfully affect the costs outcome regardless of how the substantive claims are ultimately decided.
4. Get a costs estimate that accounts for the risk of a mixed outcome, not just a best-case scenario, when budgeting for litigation.

Frequently asked questions