Court Cases & Orders

When Non-Disclosure Backfires: Ontario Court of Appeal Upholds Major Award in Mullin v Sherlock

Written by Russell Alexander ria@russellalexander.com / (905) 655-6335

Failure to disclose financial information in family law is not a technical mistake. It can determine the outcome of a case.

A recent Ontario Court of Appeal decision in Mullin v Sherlock reinforces that point in a big way. The Court upheld a significant financial award after striking the payor’s pleadings for non-disclosure, leaving the court to decide the case largely on the recipient’s evidence.

The Case in Context

In Mullin v Sherlock, the parties cohabited for approximately 12.5 years. The recipient left her career in architecture to work in the payor’s business.

By the time of litigation:

  • the recipient was earning about $30,000 per year
  • the payor was earning approximately $675,000 per year

The trial judge awarded substantial relief, including findings grounded primarily in unjust enrichment and joint family venture principles, along with spousal support. The Court of Appeal upheld those outcomes.

Non-Disclosure Can End Your Case

One of the most important aspects of this decision is procedural, not just financial.

The payor failed to properly disclose financial information. As a result:

  • his pleadings were struck
  • he lost the ability to fully advance his position
  • the court proceeded largely on the recipient’s evidence

This is a serious consequence. Once pleadings are struck, the case effectively becomes one-sided.

The message from the Court is clear: financial disclosure is not optional. It is foundational.

Unjust Enrichment Still Drives Outcomes in Non-Married Relationships

Because the parties were not married, property division did not proceed under equalization. Instead, the court relied heavily on unjust enrichment and joint family venture analysis.

The court found that:

  • the recipient contributed significantly to the payor’s success
  • she made career sacrifices that benefited the relationship
  • it would be unfair for the payor to retain the full economic gain

The result was a multi-million dollar award to address that imbalance.

Spousal Support Still Applies and Can Be Significant

Spousal support was also awarded in addition to the unjust enrichment findings.

The court:

  • recognized both compensatory and non-compensatory entitlement
  • considered the significant income disparity
  • applied the Spousal Support Advisory Guidelines at the higher end

A lump sum approach was used, reflecting:

  • a roughly 10-year duration
  • a high-end SSAG calculation
  • credit for interim payments already made

Even after those credits, the remaining award was substantial.

High Income + Low Disclosure = High Risk

This case highlights a dangerous combination:

  • very high income on one side
  • incomplete or inadequate disclosure

Where that happens, courts are prepared to:

  • draw adverse inferences
  • accept the other party’s evidence
  • impose significant financial consequences

The risk is not just losing an argument. It is losing control of the entire case.

Why This Case Matters

Mullin v Sherlock is important for three reasons:

  • Courts will enforce disclosure obligations aggressively
  • Unjust enrichment remains a powerful remedy in long-term common law relationships
  • High-income support cases will often result in top-end outcomes, especially where one party has limited earning capacity

The Bottom Line

This decision is a reminder that family law outcomes are shaped as much by conduct as by legal principles.

If you are involved in a dispute:

  • full and timely financial disclosure is critical
  • attempts to withhold or delay information can backfire
  • courts will not hesitate to impose significant consequences

In high-income cases, those consequences can be measured in hundreds of thousands or even millions of dollars.

For more commentary on Ontario family law decisions, spousal support, and property claims in common law relationships, visit FamilyLLB.com or connect with Russell Alexander Collaborative Family Lawyers.

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About the author

Russell Alexander

Russell Alexander is the Founder & Senior Partner of Russell Alexander Collaborative Family Lawyers.