Ontario Court Rules Negligence Claim Against Estate Lawyer is a Collateral Attack on Probate, Dismissing Lawsuit

Ontario Court Rules Negligence Claim Against Estate Lawyer is a Collateral Attack on Probate, Dismissing Lawsuit

CASE: Cooke Family Trust et al v. Dioguardi et al, 2025 ONSC 370

In Cooke Family Trust et al v. Dioguardi et al, 2025 ONSC 370, the plaintiffs, Alan Cooke (as trustee and litigation guardian for his children’s trusts), initiated a negligence action against lawyer Paul Dioguardi and his law firm for allegedly drafting a will that resulted in a partial intestacy. James Cooke, the testator, had engaged Dioguardi to update his will in 2018. The will provided that if his wife Patricia predeceased him or died within 30 days of his death, the estate would be distributed among his three sons and two family trusts for his grandchildren. However, Patricia survived James Cooke for over six years, which resulted in an unaddressed contingency in the will.

James Jr., one of James Cooke’s sons, was named executor and successfully obtained a Certificate of Appointment of Estate Trustee with a Will (CAETW) in May 2018 without any objection from Alan or his other brother, Jonathan. In 2020, Alan initiated a claim against Dioguardi, alleging that the negligent drafting of the will deprived his children’s trusts of the 10% shares they were meant to receive. Additionally, Alan sought a court declaration that the intestacy provisions of Ontario’s Succession Law Reform Act applied to distribute the estate’s residue.

The Ontario Superior Court, presided over by Justice Kaufman, granted summary judgment in favor of the defendants, concluding that the negligence action constituted a collateral attack on the CAETW. The court ruled that probate conclusively affirms a will’s validity, including the testator’s knowledge and approval of its contents. Since the plaintiffs’ claim contradicted the probate findings, the lawsuit was dismissed. The court also ordered the plaintiffs to pay $20,000 in costs to the defendants.

Analysis: Probate and the Effect of the Court Order

The central legal issue in this case revolved around probate and its conclusive effect on a will’s validity and contents. The court’s ruling is significant for several reasons:

1. The Legal Effect of a CAETW (Probate)

A Certificate of Appointment of Estate Trustee with a Will (CAETW) serves as judicial confirmation that:

• The will was properly executed.
• The testator knew and understood the contents of the will.
• The will is valid in all respects.

By granting probate, the court effectively confirmed that James Cooke’s will reflected his intentions and that it was legally sound. Once issued, probate operates in rem (binding on all parties, including third parties), meaning it cannot be indirectly challenged unless set aside.

The plaintiffs attempted to circumvent this by arguing that while they accepted probate, they could still sue the lawyer for negligence. However, the court rejected this argument, holding that allowing the lawsuit to proceed would require re-litigating whether James Cooke had actually intended to include gifts to his grandchildren—a direct contradiction of the probate order.

2. Collateral Attack on the Probate Order

The court found that the negligence claim amounted to a collateral attack on the CAETW. A collateral attack occurs when a party tries to indirectly challenge a final court decision instead of using proper legal channels, such as an appeal or rectification application.

Since probate confirmed the validity of the will, the plaintiffs should have:

• Opposed the probate application when it was made.
• Sought rectification of the will under Ontario estate law if they believed the will did not reflect James Cooke’s true intentions.

By failing to do so, the plaintiffs effectively accepted the will as drafted. The court ruled that it would be inappropriate to allow them to now challenge its validity through a negligence lawsuit.

3. The Inconsistency with Alan Cooke’s Other Legal Position

Another critical issue was Alan Cooke’s contradictory legal positions:

• In his separate court application, Alan sought to have the estate’s residue distributed under Ontario’s intestacy laws.
• In the negligence lawsuit, he argued that his father intended for specific gifts to be made to his grandchildren.

The court pointed out that these positions were mutually exclusive. If James Cooke had intended for his grandchildren to receive 10% of the residue each, then rectification—not intestacy—would have been the proper legal remedy. Allowing the negligence lawsuit to proceed would have led to legal inconsistency and potential double recovery.

4. The Consequences of the Court’s Decision

• Finality of Probate: The decision reinforces the principle that once a will has been probated, its validity is final unless properly set aside.
• Importance of Timely Objections: Beneficiaries who believe a will was improperly drafted must object to probate or seek rectification promptly. Delays can limit legal options.
• Limits on Professional Negligence Claims: While lawyers can be sued for negligence, courts will not entertain claims that contradict a validly probated will. Instead, affected parties must challenge probate first.

Conclusion

The court’s ruling in Cooke Family Trust et al v. Dioguardi et al underscores the binding effect of probate and the limited ability to challenge a will after a CAETW has been granted. The negligence claim was dismissed because it implicitly challenged the probate order, making it a collateral attack. The case highlights the importance of raising objections to probate in a timely manner and demonstrates that courts will prioritize finality and legal consistency over belated claims of drafting errors.

NOTE: The 15-year ultimate limitation period for negligence claims against will drafters begins from the date of the negligent act or omission—specifically, the drafting of the will—rather than the date of death. Tessa v Gora  2024 ONSC 198