Expert evidence plays a crucial role in family law disputes, particularly in cases involving child and spousal support, vocational assessments, and financial matters. However, because expert evidence is a form of hearsay, courts must ensure that it meets strict legal standards before it is admitted. The leading case on this issue is White Burgess Langille Inman v. Abbott and Haliburton Co., 2015 SCC 23, which outlines the legal framework for assessing expert testimony.
Understanding the Nature of Expert Evidence
Unlike fact witnesses, experts provide opinions based on specialized knowledge rather than direct observations. Since hearsay evidence is generally inadmissible, an exception must be made for expert testimony when it meets specific legal criteria.
The Mohan Test for Admissibility of Expert Evidence
The Supreme Court of Canada established in R. v. Mohan, 1994 CanLII 80 (SCC), a four-part threshold test for determining the admissibility of expert opinion evidence:
- Relevance – The evidence must relate directly to an issue in the case.
- Necessity – The expert’s testimony must provide insight beyond the general knowledge of the judge or jury.
- Absence of an Exclusionary Rule – The evidence must not be prohibited by other legal principles.
- Properly Qualified Expert – The individual must have the necessary education, training, and experience to provide reliable opinions.
Judicial Gatekeeping and the Balancing Test
Even if an expert meets these four criteria, a judge must conduct a gatekeeping function, weighing the potential benefits of admitting the evidence against any risks, such as misleading the court or causing undue delays.
Expert Duty: Impartiality, Independence, and Absence of Bias
As emphasized in White Burgess, experts owe a duty to the court, not to the party that retains them. Their opinions must be:
- Impartial – An objective assessment of the facts.
- Independent – Not influenced by the retaining party.
- Unbiased – Not favoring one party’s position over another.
A key test is whether the expert’s opinion would remain the same regardless of who hired them.
Application in Family Law: Vocational Assessments
A recent Ontario family law case applied these principles to vocational assessments, which are used to determine a party’s earning capacity for child and spousal support calculations. The court considered whether a vocational expert’s testimony was admissible under White Burgess/Mohan and found that:
- The evidence was relevant to whether income should be imputed.
- It was necessary as the judge lacked specialized knowledge in employment capacity assessments.
- There was no exclusionary rule preventing its use.
- The expert was properly qualified, possessing extensive experience and relevant credentials.
Key Takeaways for Family Law Practitioners and Litigants
- Ensure expert witnesses meet the Mohan criteria before seeking their admission.
- Scrutinize opposing experts for bias or lack of qualifications.
- Consider vocational assessments in spousal and child support cases to justify income imputation.
- Use White Burgess principles to challenge unreliable or partial expert testimony.
Conclusion
Expert evidence can be a powerful tool in family law disputes, but it must meet strict admissibility standards. Lawyers should be prepared to argue for or against the inclusion of expert testimony based on the Mohan test and the principles established in White Burgess. Understanding these legal frameworks ensures that expert evidence is used effectively and fairly in family law litigation.
If you’re navigating a family law case involving income calculations and requirements of expert evidence, consulting with an experienced Ontario family lawyer can help clarify how the courts may assess your financial situation.
DISCLAIMER:
The information provided in this blog is for general informational purposes only and does not constitute legal advice. No attorney-client relationship is established through this writing. You should consult with a qualified attorney for advice tailored to your specific situation. The lawyer and their firm disclaim any liability arising from reliance on this blog or any other content on this website.