Case snapshot
At a glance
- Case
- Can a Partner Be Liable for Hiding Offers on a Shared Property in Ontario?
- Court / Tribunal
- Ontario Superior Court of Justice
- Citation
- 2026 ONSC 3637 ↗
- Date
- July 8, 2026
- Area of law
- Wills Estates
- Key issue
- Whether a real estate partnership existed between co-owners and, if so, whether one partner breached fiduciary duties by concealing third-party offers and obtaining an agreement through deceit.
- Outcome
- The court granted summary judgment finding a partnership existed, set aside the agreement as obtained by deceit, and found the defendants liable for breach of fiduciary duty and unlawful means conspiracy, with damages to be determined at a later stage.
- Why it matters
- Anyone who co-owns or jointly manages property with another person in Ontario may unknowingly be in a legal partnership — and that comes with serious duties of honesty and disclosure that courts will enforce.
Legal principle
The rule from this case
Under Ontario's Partnerships Act, a partnership can exist even without a formal written agreement. Courts look at whether the parties shared management responsibilities, profits, and losses. If those elements are present, the law treats the arrangement as a partnership regardless of what the parties called it. Once a partnership is found to exist, each partner owes the others a fiduciary duty — a duty of loyalty and full disclosure. That means a partner cannot secretly deal with third parties in a way that benefits themselves at the expense of their co-partners. When a partnership is being wound up, that duty survives until the process is complete. A partner who conceals material facts — such as outside offers on shared property — can be held liable to account for any resulting loss.
Important limits
What this does not mean
This decision does not mean that every co-ownership arrangement automatically becomes a partnership. Courts still look carefully at the specific facts: how the property was managed, how income and expenses were divided, and how the parties conducted themselves. Simply owning property jointly with someone else, without shared management or profit-sharing, is not enough on its own. The ruling also does not establish a new legal test. It applies well-settled principles from the Partnerships Act and existing case law on fiduciary duty and civil fraud. What it reinforces is that courts will look past labels and written agreements — especially when one party has used deceit to obtain a favourable document — and will grant meaningful relief, including setting aside agreements entirely, when the facts support it.
Can two people be in a partnership without a written agreement in Ontario?
Yes — Ontario law can recognize a partnership even when there is no formal written contract. Under the Partnerships Act, the key question is whether the parties were carrying on a business together with a view to profit. In Macgillivray v. Poirier, 2026 ONSC 3637 (CanLII), the court applied this test to a shared real estate arrangement and found that a partnership existed based on how the parties actually behaved.
The court looked at evidence of shared management, shared profits and losses, and admissions made by the parties themselves. When those elements were present, the legal label the parties used — or didn’t use — did not matter. This is a reminder that informal arrangements can carry serious legal consequences.
What fiduciary duties does a partner owe in Ontario?
A partner owes co-partners a fiduciary duty, meaning a duty of loyalty and full, honest disclosure. This is one of the most demanding standards in Ontario law. A partner cannot put their own interests ahead of the partnership or hide information that would affect how the others make decisions.
In this case, the court found that one party concealed third-party offers related to the shared property. That concealment was a breach of the duty to disclose material facts to the firm. Importantly, the Partnerships Act confirms that this duty survives the winding-up of a partnership — partners cannot escape accountability simply because the business relationship is ending.
Can a court set aside an agreement signed under deceit in Ontario?
Yes — an agreement obtained through false statements that induced someone to sign it can be set aside entirely. Ontario courts have long recognized rescission as a remedy when one party has been deceived into entering a contract. The court in this case relied on established authority confirming that deceit vitiates consent.
Here, the agreement — along with a power of attorney — was found to have been obtained through misrepresentation. The court set it aside and held that it could not be used by the defendants to support their position. This is sometimes called a “boomerang” judgment: the very document the defendants relied on was turned against them.
What is unlawful means conspiracy and when does it apply?
Unlawful means conspiracy occurs when two or more people act together using unlawful conduct to cause harm to another person. It is a civil wrong, not a criminal charge, and it can result in damages being awarded against all participants jointly and severally — meaning each person can be held responsible for the full amount.
In this case, the court found that the defendants acted in concert to secure an unequal share of sale proceeds. The unlawful acts included the breach of fiduciary duty and the deceit used to obtain the agreement. Causation and loss were established, making all defendants liable. Our Ontario wills and estates lawyers regularly advise clients on disputes where shared property and trust obligations intersect.
What happens when a partner hides offers on shared property?
When a partner conceals material offers on jointly held property, they expose themselves to liability to account — meaning they may have to pay over any benefit they gained at the expense of the partnership. The court in this case found that liability was established and ordered that the quantum (the dollar amount) be determined at a later stage.
This kind of remedy is designed to strip the wrongdoer of any unjust gain. It is not limited to the direct loss suffered by the other partner; it can extend to profits the wrongdoer made by exploiting the concealed information. Anyone involved in a dispute over shared property in the Burlington or Hamilton area should seek legal advice promptly, as delay can affect the remedies available.
Practical takeaways for property co-owners
- Get it in writing. If you are managing property with someone else and sharing costs or profits, document the arrangement carefully. Courts will find a partnership whether or not you intended one.
- Disclose all offers. If you receive any offer or expression of interest related to jointly held property, share it with your co-owner immediately. Concealment can constitute a breach of fiduciary duty.
- Watch for red flags. If a co-owner pressures you to sign documents quickly, consult a lawyer before signing. An agreement obtained through misrepresentation can be set aside, but it is better to avoid the dispute entirely.
- Fiduciary duties survive the end of the relationship. Even after you have agreed to wind up a shared arrangement, your duty of loyalty and disclosure continues until the process is complete.
- Act quickly if you suspect wrongdoing. Remedies like rescission and an accounting are powerful, but courts expect parties to move promptly once they discover a problem. If you are based in the Hamilton or Burlington area, our wills and estates team in Burlington can advise on your options.
Why does this decision matter for estate and property disputes in Ontario?
This ruling matters because it shows that Ontario courts will look past paperwork — and even past signed agreements — to find the true nature of a relationship and correct an injustice. The combination of findings here (partnership, fiduciary breach, rescission, and conspiracy) gives the affected party a strong platform for recovery at the damages stage.
For anyone involved in a co-ownership arrangement, whether through a family estate, an investment property, or an informal business venture, this case is a clear signal that the law takes honesty between co-owners seriously. If you believe a co-owner has hidden information or manipulated documents to gain an advantage, you may have more legal options than you think. Explore your rights with our Ontario estate and property dispute lawyers to understand what remedies may be available to you.
UL Lawyers offers a free initial consultation from our Burlington office and serves clients across Ontario. If you are dealing with a partnership dispute, a breach of fiduciary duty, or a co-ownership conflict, reach out to our wills and estates team to discuss your situation.
This article is automated commentary on a public court decision and is for general information only — not legal advice. Decisions rely on facts unique to each case. If you are affected by a similar issue, contact a lawyer for advice specific to your situation.
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