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What Happens When Your Prenuptial Agreement Is Challenged Under Ontario Law

This is general information and should not be interpreted as legal advice. Contact a family law lawyer to understand your rights and obligations.

Prenuptial agreements, commonly called “pre-nups,” are an important planning tool for couples entering marriage. When properly drafted, they can provide clarity, protect assets, and reduce conflict if a relationship later breaks down. However, in Ontario, a prenuptial agreement is not automatically immune from challenge.

This blog explains what happens when a prenuptial agreement is challenged under Ontario law, the common grounds for challenge, and how courts decide whether the agreement will be upheld.

What Is a Prenuptial Agreement in Ontario?

Under Ontario’s Family Law Act, a prenuptial agreement is a type of domestic contract entered into before marriage. It can address issues such as:

• Division or exclusion of property

• Treatment of business interests or inheritances

• Spousal support obligations

• Financial responsibilities during the marriage

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While parties have significant freedom to contract, Ontario law places limits on what a pre-nup can cover and how it must be created.

When Is a Prenuptial Agreement Typically Challenged?

A prenuptial agreement is most often challenged after separation or divorce, when one party seeks to avoid or change the financial outcome set out in the contract. Challenges commonly arise where there is a significant imbalance in assets, income, or bargaining power, or where circumstances have changed dramatically since the agreement was signed.

Legal Grounds for Challenging a Pre-Nup in Ontario

Ontario courts will not set aside a prenuptial agreement lightly, but they will do so where legal requirements were not met or where enforcing the agreement would be unfair. Common grounds include the following.

1. Lack of Full Financial Disclosure

Each party must provide honest and complete disclosure of their assets, debts, and income before signing the agreement. If one party failed to disclose significant assets or liabilities, the court may set aside all or part of the agreement. Full disclosure is fundamental because parties cannot make informed decisions without knowing the true financial picture.

2. Duress, Coercion, or Pressure

A pre-nup must be entered into voluntarily. If one party was pressured, threatened, or placed under unfair time constraints, the agreement may be invalid. Examples include presenting the agreement shortly before the wedding or implying the marriage would be cancelled unless it was signed.

3. Lack of Independent Legal Advice

While not strictly mandatory under the Family Law Act, independent legal advice is a key factor courts consider. If one party did not understand their rights or the consequences of the agreement, and did not receive proper legal advice, the agreement is more vulnerable to challenge.

4. Unconscionability

Ontario courts may intervene where an agreement is unconscionable, meaning it is extremely unfair and the result of unequal bargaining power. This can arise where one party exploited the other’s vulnerability, lack of education, language barriers, or financial dependence.

5. Improper Execution

For a pre-nup to be valid, it must be in writing, signed by both parties, and witnessed. Failure to meet these formal requirements can render the agreement unenforceable.

Limits on What a Pre-Nup Can Decide

Even a properly drafted prenuptial agreement cannot address every issue. Under Ontario law:

• A pre-nup cannot determine child custody, decision-making responsibility, or child support.

• Provisions that attempt to limit child support will be disregarded if they are inconsistent with the child’s best interests or the Child Support Guidelines.

If a challenged agreement includes invalid provisions, the court may strike those

clauses while enforcing the remainder, depending on the circumstances.

How Ontario Courts Decide Whether to Uphold a Pre-Nup

When a pre-nup is challenged, the court conducts a two-stage analysis. First, it examines whether the agreement meets the legal requirements under the Family Law Act. Second, it considers whether enforcing the agreement would be unfair in light of the parties’ circumstances.

Courts place significant weight on the principle that adults are entitled to arrange their financial affairs as they see fit. However, they will balance this against the need for fairness, transparency, and protection from exploitation.

Importantly, a court will not set aside a pre-nup simply because one party regrets the deal or because the outcome is financially disadvantageous. There must be a legal basis for the challenge.

What Happens If the Pre-Nup Is Set Aside?

If a court sets aside all or part of a prenuptial agreement, the issues it was meant to address will be decided under Ontario family law instead. This may include:

• Equalization of net family property

• Determination of spousal support based on statutory factors

• Court discretion replacing contractual terms

Protecting Your Prenuptial Agreement

If you are considering a prenuptial agreement, or if you are facing a challenge to an existing one, early legal advice is essential. Addressing issues proactively can make the difference between an agreement that provides certainty and one that becomes the subject of costly litigation.

Seeking Legal Support

Prenuptial agreements can be powerful tools under Ontario law, but they are not absolute. When challenged, courts will closely examine how the agreement was made and whether it should be enforced. Understanding your rights and obligations is critical at every stage, from drafting to enforcement.

Majoka Law assists clients with negotiating, drafting, enforcing, and challenging prenuptial agreements, always with a focus on clarity, fairness, and long-term protection.