- A lawyer's duty is to act in their client's best interest, keep their client's information confidential, and give independent advice.
- As a general rule, a lawyer or law firm cannot act for both the buyer and the seller in the same arm's-length real estate transaction.
- Ontario's professional conduct rules do recognize narrow circumstances where a lawyer may act for more than one party to a transaction — generally requiring full disclosure of the…
It's a common question once two parties reach a deal, especially when the buyer and seller already know each other: can they just use one lawyer and split the cost? In most Ontario real estate transactions, the answer is no — and understanding why matters more than just knowing the rule.
Ontario lawyers are bound by the Law Society of Ontario's professional conduct rules, which are built around avoiding conflicts of interest. A home purchase is a classic example of two parties with opposing interests: the seller wants the highest price and fewest conditions, while the buyer wants protections, disclosures, and the lowest price. One lawyer cannot fully advocate for both at once.
Why the Conflict Rule Exists
A lawyer's duty is to act in their client's best interest, keep their client's information confidential, and give independent advice. In a purchase and sale, the buyer and seller frequently have information, priorities, and risks that directly conflict:
- The seller may know about property issues the buyer needs disclosed.
- The buyer may want to negotiate price or conditions the seller wants to resist.
- Each side may need confidential advice the other side shouldn't see.
A single lawyer acting for both sides can't fully serve either client without compromising the other's interests — which is exactly what the conflict-of-interest rules are designed to prevent.
The General Rule
As a general rule, a lawyer or law firm cannot act for both the buyer and the seller in the same arm's-length real estate transaction. This isn't a matter of preference or convenience — it flows from the Law Society of Ontario's professional conduct requirements, which govern how every Ontario lawyer must handle situations where clients' interests diverge.
This is distinct from the rules governing realtors. Under TRESA, a real estate brokerage can, in some circumstances and with proper disclosure, represent both a buyer and seller in the same transaction (multiple representation) — but that TRESA framework doesn't extend to lawyers, who are separately regulated by the Law Society of Ontario and held to their own conflict rules.
Are There Any Exceptions?
Ontario's professional conduct rules do recognize narrow circumstances where a lawyer may act for more than one party to a transaction — generally requiring full disclosure of the conflict, and informed, voluntary consent from every affected client, along with an honest assessment of whether the lawyer can still represent each client's interests adequately. These situations are limited and fact-specific, and the more cautious, common practice is to decline dual representation on an arm's-length home purchase rather than rely on an exception. If you're ever asked to consent to a lawyer acting for "both sides," ask direct questions about what that means for your ability to get independent advice — or simply retain your own lawyer instead.
What Buyers and Sellers Should Do Instead
| Situation | Recommended approach |
|---|---|
| Arm's-length purchase (unrelated buyer/seller) | Each side retains its own lawyer |
| Buyer and seller are family members | Still generally retain separate lawyers; ask about any disclosed conflict |
| Buyer and seller want to "save money" on legal fees | Compare flat-fee options — separate representation is normal practice, not an added expense to avoid |
| Multiple properties, one deal (for example, a swap) | Separate lawyers for each side of each transaction |
Retaining separate lawyers isn't about mistrust between the buyer and seller — it's about each party having someone whose only job is to protect their interests, catch issues in title, financing, and closing mechanics, and give advice that isn't shaped by also representing the other side.
Frequently asked questions
If I'm buying from a family member, can we still use one lawyer?
Generally, no — even close family relationships involve financial terms, disclosures, and closing mechanics where interests can diverge. Most lawyers will still recommend, or require, separate representation, though any conversation about a disclosed exception should happen directly with the lawyers involved.
Does using separate lawyers cost more overall?
Not necessarily. Many Ontario real estate lawyers, including Treadstone Law, offer flat, transparent fees for a standard purchase or sale, so the cost of proper representation is predictable up front.
Can the seller's lawyer explain a document to me if I don't have my own lawyer yet?
A seller's lawyer represents the seller only and cannot give you legal advice, even informally. If you don't yet have a lawyer, that's a signal to retain one before signing anything or relying on explanations from the other side's counsel.
What if the buyer and seller already agree on everything?
Even where a deal seems fully agreed, separate lawyers still review title, confirm the legal description, handle mortgage discharges and registrations, prepare the statement of adjustments, and catch issues neither party may have thought to raise. Agreement on price doesn't remove the need for each side's own legal review.
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