Conflict of Interest with a Common Lawyer: What the Court of Cassation Says

Imagine the scene: in Nœux-les-Mines, a married couple decides to sell the family home. Problem? The husband alone signs the preliminary contract, without his wife's written consent. The buyer notices this and refuses to go further, citing a conflict of interest between the spouses, who are both represented by the same lawyer. A situation that would make any homeowner bristle: can one really withdraw from a sale on the pretext that the seller and his wife share the same legal counsel?

This question was answered by the Court of Cassation on 31 March 2010 in a landmark case (No 08-19.649). It ruled decisively: the opposing party is not entitled to rely on a potential conflict of interest between parties represented by the same lawyer. Only those clients can raise it. A decision that secures property transactions, but raises questions about lawyers' vigilance.

In this article, I tell you the background of this case, analyse the judges' reasoning, and give you the keys to avoid finding yourself in a similar legal deadlock, whether you are a seller, buyer or professional in Bully-les-Mines or elsewhere.

The Facts: A Story That Happens Every Day

It all begins in the jurisdiction of Béthune, in Nœux-les-Mines. Mr and Mrs X wish to sell their house. They entrust the sale to a single lawyer, Maître Z. A preliminary contract is signed with a buyer, Mr Y. But here's the thing: only Mr X signed the deed. His wife did not give her written consent. Article 1424 of the Civil Code (which requires the consent of both spouses to sell community property) was not complied with.

The buyer, Mr Y, sensing an opportunity, withdraws. He argues that the presence of a single lawyer for both spouses creates a conflict of interest: the lawyer could not defend both the husband (who wanted to sell alone) and the wife (whose consent was missing). According to him, this conflict vitiates the sale and justifies his withdrawal.

The X spouses, determined to sell, sue Mr Y to compel him to complete the sale. The Tribunal de Grande Instance of Strasbourg rules in their favour at first instance. Mr Y appeals, but the Court of Appeal upholds the judgment. The case goes up to the Court of Cassation, which dismisses the buyer's appeal. The judicial saga lasts several years, but in the end, the sale must go ahead.

The Reasoning of the Court — Analysed

The Court of Cassation relies on a simple principle: standing to sue. To challenge a conflict of interest, one must be the person directly concerned. Here, it is the X spouses who are represented by the same lawyer. Only they have the right to complain about a potential conflict. The buyer Mr Y, as the opposing party, has no legitimate interest to do so. He cannot use this pretext to free himself from his commitment.

The High Court recalls that Article 1424 of the Civil Code requires the consent of both spouses to alienate community property (sell, mortgage, etc.). But this consent can be given tacitly or through subsequent acts. In this case, Mrs X had manifested her intention to sell by signing other documents. The lack of signature on the preliminary contract was not an insurmountable obstacle.

What is striking is that the Court does not rule on the actual existence of a conflict of interest. It simply says that Mr Y cannot invoke it. It is a question of procedure, not ethics. But implicitly, it validates the practice of a single lawyer for selling spouses, provided they are consenting. A strong signal for professionals.

This decision confirms consistent case law: the Court of Cassation protects contractual freedom and the security of transactions. It refuses to allow outside third parties to challenge an agreement by hiding behind internal rules of the couple. A position that may be surprising, but prevents abuses.

What This Changes for You — Practically

For selling owners (in Nœux-les-Mines, Bully-les-Mines or elsewhere): You can now be represented by a single lawyer, even if you are a couple. Your spouse can give informal consent (email, oral exchange) or confirm it afterwards. The buyer cannot withdraw by invoking an imaginary conflict of interest. Concrete example: if you sell a property for €250,000 and the buyer refuses to sign the final deed, you can compel him in court without fearing that he will use this argument.

For buyers: Beware, you cannot use this pretext to back out. If you change your mind, you risk damages for wrongful withdrawal. In Bully-les-Mines, a buyer who withdraws after signing a preliminary contract may be liable for up to 10% of the price (i.e., €25,000 on €250,000). Better check the validity of the preliminary contract before signing.

For professionals (estate agents, notaries): This decision simplifies your files. You can accept a single mandate for a couple, even if only one spouse signs. But remain cautious: if you have any doubt about the spouse's consent, have it confirmed in writing. An email suffices, but keep it.

For co-owners: The same principle applies to co-ownership. A single lawyer can represent all co-owners, unless one expressly objects. The buyer cannot invoke a conflict between co-owners to withdraw.

Four Tips to Avoid This Type of Dispute

• Obtain your spouse's written consent before signing: Even if the law does not require it for all acts, a writing (signature on the preliminary contract, email, letter) avoids any challenge. In Nœux-les-Mines, a simple email from Mrs X to the lawyer would have cut short the dispute.
• Have your lawyer's qualification checked: Before appointing a single lawyer for a couple or co-ownership, ask him if he identifies a conflict of interest. If he says no, have it confirmed in writing. If in doubt, take one lawyer per party.
• Never withdraw on a mere suspicion: If you are a buyer and want to cancel a sale, consult a lawyer. A conflict of interest raised without grounds can cost you dearly (damages, legal costs).
• Archive all communications: Keep emails, letters, meeting minutes. In case of a dispute, these pieces of evidence are crucial. A client recently showed me a text message from his spouse saying "OK for the sale": that was enough to convince the court.

Further Reading: Related Case Law and Developments

This decision is part of a protective line of the parties' will. In 2005, the Court of Cassation already held (Civ. 1ère, 8 November 2005, No 03-10.257) that the lack of spousal consent does not render the sale null and void automatically: the spouse must act himself. More recently, in 2018 (Civ. 3ème, 14 June 2018, No 17-18.914), the Court specified that a buyer in good faith can require the completion of the sale if the spouse later ratified the deed.

The trend is therefore towards securing property transactions. The courts favour contract stability over procedural technicalities. For the future, we can expect judges to be even stricter on the standing of third parties to act. If you are a professional, know that this case law is your shield against wrongful withdrawals.

One grey area remains: lawyers' ethics. The Bar's internal regulations prohibit representing clients with conflicting interests without informing them. But here, the spouses had a common interest (selling). The Court of Cassation did not rule on this point, leaving it to professional bodies to regulate.

In Practice: What to Do

FAQ: 5 Questions to Act

• Can I sell community property without my spouse's written consent? Yes, if you prove his consent by other means (email, text message, testimony). But to avoid any risk, have him sign the preliminary contract.
• Can the buyer withdraw for conflict of interest? No, according to this decision. He must prove actual harm, which is rare.
• What if the buyer wrongfully withdraws? Sue him to compel the sale or claim damages. Legal fees (approx. €1,500 to €3,000) are often recoverable.
• Do I need a separate lawyer for my spouse? Not mandatory, but advisable if you have conflicting interests (e.g., one spouse wants to sell, the other does not). Otherwise, a single lawyer suffices.
• What are the time limits to act? To challenge a sale, you have 5 years from the discovery of the conflict (limitation period). But in practice, act quickly: eager buyers do not wait.

Are you in a similar situation? A first 30-minute consultation with Maître Zakine (€45) can save you months of litigation — and often much more. Book an appointment →