Adding or Removing a Party to an Ontario Lawsuit

Lawsuits do not always start with exactly the right cast of characters. Sometimes a plaintiff discovers, partway through, that a related company — not the one originally named — actually signed the contract. Sometimes a defendant is sued who has no real connection to the dispute at all. Ontario's civil process anticipates both problems: a party can generally be added to, or removed from, an existing lawsuit rather than forcing everyone to start over with a brand-new action.

Getting this right matters more than it might seem. Add party to lawsuit ontario procedures interact directly with limitation periods, service requirements, and how the rest of the case proceeds — mishandling it can mean losing the ability to pursue (or properly defend against) a claim altogether.

Why a Party Might Need to Be Added

• A necessary party was left out. Some claims cannot be fully or fairly resolved without a particular person or company as part of the case — for example, a co-owner of property at the centre of the dispute.
• The wrong legal entity was named. A plaintiff may have sued an individual instead of the corporation that actually contracted, or named a numbered company instead of its operating name, without realizing the distinction mattered.
• New facts reveal another responsible party. Discovery of documents or examinations can reveal that someone not originally sued should be part of the case — sometimes handled through a third party claim rather than simply adding a new defendant.
• A party's role changes. An estate trustee may need to be substituted in after an original party dies, or a corporate successor may need to be added after a merger or sale affecting one of the parties.

Adding a Party — The General Approach

1. Identify precisely who needs to be added and why — as a plaintiff, defendant, or in another capacity.
2. Check whether the applicable limitation period affects adding this specific party; adding a new defendant after the limitation period has run is far more difficult than doing so while time remains.
3. Bring a motion (or, in straightforward cases, follow a simpler amendment process) asking the court to add the party, generally supported by an explanation of why the addition is necessary.
4. Once added, ensure the newly added party is properly served with the pleading naming them, just as any defendant would be at the start of a case.
5. Allow the newly added party the normal opportunity to respond — filing a defence, or otherwise participating, on essentially the same footing as an original party.

Removing a Party — The General Approach

A party can be removed from a lawsuit where it becomes clear they should never have been included, or where their involvement is no longer necessary. This can happen because:

• The plaintiff agrees to discontinue the claim against that specific defendant, often because it becomes clear during the case that the wrong entity was named or that defendant bears no responsibility.
• A motion to strike or a summary judgment motion succeeds specifically against that party, ending the claim against them while the case continues against others.
• The parties settle with one defendant while the case continues against the remaining defendants.

Removing a party generally does not affect claims that continue against the others, and a defendant who is removed early — before significant costs are incurred — is often in a stronger position to recover their own costs of having been unnecessarily drawn into the case.

Misnomer: Fixing a Simple Naming Mistake

Sometimes what looks like "adding a party" is really just correcting a name — suing "ABC Contracting" when the actual legal entity is "ABC Contracting Inc." This kind of correction (often called fixing a misnomer) is generally treated more leniently than adding a genuinely new party, since the real target of the lawsuit was clear all along and the mistake was essentially clerical. Courts are typically more willing to allow this kind of fix even close to or after a limitation period has expired, compared to adding someone who was never previously identified as a target at all — though this remains fact-specific and is not guaranteed.

Checklist Before Bringing a Motion to Add or Remove a Party

• [ ] Confirm the exact legal name and status of the party being added (individual, corporation, partnership, estate)
• [ ] Check the current status of the applicable limitation period for that specific party
• [ ] Determine whether this is truly "adding a new party" or simply "correcting a misnomer" — the two are treated differently
• [ ] Consider whether a third party claim, rather than simply adding a defendant, better fits the situation
• [ ] Prepare to explain to the court why the addition or removal serves the real issues in the case, not a tactical advantage
• [ ] Confirm how the change affects existing deadlines — service, defence timelines, and any scheduled mediation or examinations

Frequently asked questions