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Mason v Perras Mongenais: Partial Summary Judgment Revisited

Mason v Perras Mongenais: Partial Summary Judgment Revisited


Posted May 8, 2019

In the years following the landmark Supreme Court of Canada decision of Hyrniak, there has been a notable shift towards parties bringing summary judgment motions seeking full or partial summary judgment.

However, in the recent Court of Appeal decision of Mason v Perras Mongenais, the Court of Appeal revisited the rules on cases where partial summary judgment is sought, and restated its previous guidance on summary judgment being an exception, and not the rule.


Mason v Perras Mongenais (2018 ONCA 978), a recent Court of Appeal decision written by Justice Nordheimer, was an appeal of decision granting summary judgment dismissing a claim against a law firm for professional negligence.

The claim of professional negligence was brought against two law firms, including the firm of Perras Mongenais, based on the plaintiff’s incurrence of a significant tax liability following a settlement on equalization in a family law matter.

A lawyer at the firm of Perras Mongenais had been asked by the plaintiff’s family law lawyer to provide advice on the tax implications of proposed terms of settlement with respect to the equalization of shares. He had provided that advice to the family law lawyer and the settlement was executed; which triggered the tax liability.

The plaintiff claimed against his family law counsel and Perras Mongenais for professional negligence. Perras Mongenais brought a motion for summary judgment seeking to have the claim against it dismissed.

The Summary Judgment Motion

On the hearing of the summary judgment motion, the motion judge found that the lawyer had given correct advice on the tax consequences of the proposed settlement, and held that summary judgment should be granted to dismiss the claim against Perras Mongenais. In the decision granting summary judgment, the motion judge reviewed the Hyrniak decision, specifically the instructions from the Supreme Court on when partial summary judgment was appropriate.

The Appeal

On appeal, the Court of Appeal held that the motion judge erred in principle by granting partial summary judgment.

Justice Nordheimer noted that the motion judge failed to heed the advice given in previous Court of Appeal decisions (such as Baywood Homes Partnership v Haditaghi) about the risks associated with partial summary judgment. The Court of Appeal reiterated that a motion for partial summary judgment should be considered to be a rare procedure that is reserved for issues that may be readily bifurcated from those in the main action, and that may be dealt with expeditiously and in a cost effective manner.

The Court of Appeal ultimately held that the liability of Perras Mongenais could not be readily bifurcated from the rest of the claim, as it was inextricably linked to the allegations of professional negligence against the plaintiff’s family law counsel.

Justice Nordheimer also commented on the motion judge’s comments regarding a “culture shift” towards summary judgment following the decision in Hyrniak, specifically his comments on their having been a shift away from trials making them an option of last resort.

Justice Nordheimer disagreed with the extent of that “culture shift”, and noted that Hyrniak was only intended to recommend a shift away from the very restrictive use of summary judgment, but that the overriding principle remains that summary judgment is the exception, not the rule.

Key Takeaways

This decision is of significant importance for parties contemplating summary judgment motions. Specifically, Justice Nordheimer’s comments that summary judgment must be appropriate for the matter should cause parties to reflect on whether the issues to be determined by summary judgment are appropriate to be adjudicated in that way, especially given that the Court of Appeal emphasized that Courts are to still view summary judgment as an exception, and not the rule.

In light of this decision, parties should also be wary of advancing motions for partial summary judgment without careful consideration as to whether the issues for summary judgment can be readily separated. This decision makes it clear that if the issues in the matter cannot be readily separated, partial summary judgment will not be appropriate.

This blog post was written by Alexander Bissonnette, a member of the Commercial Litigation team.  He can be reached at 613-369-0358 or at


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