Executive Summary: Key Legal and Evidentiary Issues

• Michel-Ange Potvin, brother of the late Bertrand Potvin, applied to the court to verify a holographic will dated 8 May 1985 that designates him as universal legatee.
• Dominic Desgagné intervened voluntarily, claiming to be the biological son of the deceased and seeking to contest the will's validity.
• Sufficient legal interest is required to intervene in a will-verification proceeding, and that interest must be legal, direct, personal, and either vested or certain.
• Desgagné's claimed interest was contingent on first establishing his filiation, which had not been proven and must be pursued in a separate proceeding.
• Procedural abuse requires more than filing a claim in the wrong forum; vexatious or unreasonable conduct must also be established.
• Filing a claim in an inappropriate proceeding does not, on its own, constitute an abuse of process.

Facts of the case

Bertrand Potvin died in March 2023. In May 2024, his brother Michel-Ange Potvin applied to the Superior Court of Quebec (District of Joliette) to have a holographic will dated 8 May 1985 verified and declared valid. The will names Michel-Ange as Bertrand's universal legatee. Because the deceased left no descendants or surviving spouse, and all of his siblings except Michel-Ange had predeceased him, the applicant also sought a dispensation from notifying all known successors — estimated at no fewer than 45 — and requested leave to notify only one nephew or niece representing each branch of the family.

On 27 March 2025, Dominic Desgagné, who was not a party to the proceeding, filed two documents: a "Response" and a document titled "Moyens de contestation de la personne intéressée," to which he added a handwritten notation identifying it as a voluntary intervention. In these filings, Desgagné asserted that the deceased was his biological father, opposed the will-verification application, asked the court to recognize him as a rightful heir, and sought a declaration that the 8 May 1985 document was invalid. On 23 April 2025, Michel-Ange filed an opposition to the voluntary intervention, arguing that Desgagné had produced no evidence of the alleged filiation and lacked the legal standing to intervene. On 18 September 2025, Desgagné filed a further document seeking a post-mortem filiation hearing and a suspension of the will-verification proceeding pending that determination. Michel-Ange responded on 11 December 2025 with an application to have Desgagné's incidental demand declared inadmissible and abusive.

Legal framework on voluntary intervention

Under the Quebec Code of Civil Procedure, a voluntary intervention is permitted where a person has a sufficient interest in an existing proceeding to which they are not a party. That interest must be legal, direct, and personal, and must be either vested and current or, at minimum, certain. In succession matters specifically, only those who have certainty of inheriting — were the will set aside — possess the legal interest required to contest it. Children of a deceased person who could inherit on intestacy generally satisfy this standard without difficulty.

Court's reasoning and analysis

The court first addressed the timeliness of Michel-Ange's opposition. Although he filed it on 23 April 2025, beyond the prescribed 10-day window from the date of Desgagné's intervention, the court extended the deadline to that date. It did so because Michel-Ange's counsel had sought clarifications from interested parties before the original deadline expired, only a few additional days had elapsed, Desgagné suffered no prejudice from the short extension, and — critically — the question of sufficient interest is a matter of public order that the court may raise on its own initiative regardless of when an opposition is filed.

On the merits of the intervention, the court found that Desgagné had not demonstrated sufficient interest. Because his filiation to the deceased had not been established, he could not be said to have a vested, current, or even certain interest in the estate. He neither had certainty of inheriting nor was he in a position to derive a personal advantage from the outcome of the will-verification proceeding, even if that application were ultimately dismissed. The court further observed that what Desgagné was truly seeking — recognition of his filiation — was not incidental in nature but constituted an originating demand that must be brought in a separate proceeding. The will-verification application was simply not the appropriate forum for resolving questions of filiation.

On the abuse of process application, the court declined to make such a declaration. It found that Desgagné's conduct was better explained by unfamiliarity with procedural rules — he was self-represented — than by bad faith or a deliberate misuse of process. Filing a claim in the wrong proceeding does not, without more, amount to an abuse. The record disclosed no vexatious or querulous behaviour, no excessive or unreasonable use of procedure, and no intent to cause harm.

Ruling and overall outcome

The court granted Michel-Ange Potvin's opposition and rejected Desgagné's voluntary intervention, finding it lacked the legal standing required to participate in the will-verification proceeding. Desgagné's incidental demand for a filiation hearing and suspension of the main proceeding was declared moot, as he was no longer a party to the case. The application to have that demand declared abusive was dismissed, with no costs awarded on that point. Michel-Ange Potvin was the successful party overall; costs of the proceeding were awarded in his favour, though no specific monetary amount was stated in the judgment.