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  • Writer's pictureJared Davies, Lawyer

The Browne v Dunn evidence rule pursuant to De Longte v De Longte, 2023 ONSC 5512


The recent case of De Longte v De Longte provides insight into the application of the Browne v. Dunn rule in trials. This rule holds great significance in maintaining fairness in family law trials. This blog post examines the legal intricacies of the rule, the arguments presented by both parties, and the court's ultimate ruling.

The primary issue stems from the fact that the Respondent’s counsel asked questions to the Respondent that would impeach the credibility of the Applicant after the Applicant testified and without putting those questions to the Applicant:

[4] The Respondent then commenced his examination in chief. Almost immediately, the Applicant raised a number of objections regarding the questions posed to the Respondent, which were in violation of the rule in Browne v. Dunn…Counsel for the Respondent readily admitted that his failure to put the Respondent’s anticipated evidence on substantive issues to the Applicant in cross-examination, was an error on his part and not in any way a strategy of “trial by ambush”.

Legal Analysis

The Browne v. Dunn Rule

The Browne v. Dunn rule is a cornerstone of ensuring fairness in trial proceedings. This rule dictates that if a party intends to impeach a witness called by the opposing party, they must provide the witness with an opportunity, while they are testifying, to explain any contradictory evidence. The essence of this rule is to maintain fairness throughout the trial, preserve the credibility of witnesses, and ensure that the trier of fact has access to all relevant information.

In family law, this rule ensures that relevant witnesses have an opportunity to address crucial facts or documents and prevents one party from "blindsiding" the other by withholding essential information that they intend to introduce during the trial.

The court remarked:

[12] As stated in Evidence in Family Law, by Harold Niman, at para. 7:15:

If you intend to challenge the credibility of a witness you must put the disputed facts or documents to them in cross examination or run the risk of the ancient but still applied rule in Browne v. Dunne.

This is based upon the principle of fairness, so that every relevant witness shall have an opportunity to address important facts or documents. You are not permitted to “blindside” the other side of a case by remaining silent about an important and relevant fact or document which you intend to introduce in your part of the trial and thus rely upon as part of your own case. This is obvious if the “hidden” fact or document relates to credibility, but just as applicable to any other relevant portion of the case.

Considerations for Remedies

When a breach of the Browne v. Dunn rule occurs, the court has discretion in deciding the appropriate remedy. Several factors come into play when determining the remedy, including the seriousness of the breach, the context in which it occurred, the timing of the objection, the position of the offending party, the possibility of recalling witnesses, and the availability of these witnesses.

In family law proceedings, two common remedies are available when the rule is violated:

1. Consider the breach when assessing a witness's credibility and the weight of their evidence.

2. Allow counsel to recall the witness whose evidence was impeached without notice and permit them to provide evidence on the disputed issues.

Respondent's Position

The respondent argued that, given the extensive litigation history between the parties and the numerous affidavits exchanged, the alleged violations should not come as a surprise to the applicant. They contended that any perceived "unfairness" was negligible, as both parties had substantial notice of the expected evidence.

However, the respondent conceded that if the court found a violation, the most suitable remedy would be to allow the applicant and another witness to be recalled. They also assured that this would not significantly delay the trial, as two witnesses were being removed from their list.

Applicant's Position

The applicant maintained that the scope and severity of the violations were substantial, making the exclusion of the respondent's evidence the appropriate remedy. They contended that the breach struck at the heart of valuation and income issues and resulted in a trial by ambush. However, when presenting their formal submissions, the applicant failed to provide case law supporting their position for excluding the contested evidence.


The court acknowledged that a violation of the Browne v. Dunn rule had occurred but disagreed with the applicant's assertion that evidence exclusion was the right remedy. Instead, the court emphasized that this rule aims to ensure fairness in trials, not to warrant evidence exclusion.

In determining the remedy, the court considered several factors, including whether the breach was intentional, the seriousness and volume of the violations, the timeliness of the objection, and witness availability. The court also noted that the respondent's oversight was unintentional and that exclusion would be unfair.

Considering the breaches on substantive issues and the need for fairness and full disclosure, the court ruled that recalling the applicant and another witness was the appropriate remedy. This ensured that all relevant evidence was heard, and the court could assess the credibility of all witnesses accurately.

The case highlights the critical role of the Browne v. Dunn rule in maintaining fairness in family law trials. This rule serves as a reminder that all parties must provide an opportunity for witnesses to address contradictory evidence during their testimony.

In this case, the court's decision to recall witnesses rather than exclude evidence demonstrates the paramount importance of fairness in family law proceedings. This ruling ensures that the trial process remains equitable and that the court can make well-informed decisions based on all available evidence. Ultimately, the case underscores the significance of upholding the principles of fairness and transparency in family law trials, even in the face of rule violations.


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