When Is An Expert Report In Law Admissible? The Court Clarifies The Applicable Rules In Matters Of Professional Liability



Fasken is a leading international law firm with more than 700 lawyers and 10 offices on four continents. Clients rely on us for practical, innovative and cost-effective legal services. We solve the most complex business and litigation challenges, providing exceptional value and putting clients at the centre of all we do. For additional information, please visit the Firm’s website at fasken.com.
A lawyer practising in a specialized field who provides an expert opinion on their field of practice must describe and/or indicate the usual practices or standards of diligence...
Canada Tax
To print this article, all you need is to be registered or login on Mondaq.com.

A lawyer practising in a specialized field who provides an expert opinion on their field of practice must describe and/or indicate the usual practices or standards of diligence in order to assist a court in determining the existence of a professional—otherwise, their conclusions on any alleged professional misconduct will be deemed inadmissible and their expert opinion dismissed (art. 241 CCP).

In a recent judgment,1 the Honourable Florence Lucas, J.S.C., dismissed the expert opinion on tax law provided by a lawyer and professor of Université Laval (the "Expert Opinion") on the grounds that the Expert Opinion would not serve any useful purpose for the Court, as it did not meet the criteria of relevance or necessity and that the expert had encroached on the judge's role.2

The dispute centred on the alleged professional misconduct of a tax lawyer (the "Defendant") who, it was claimed, had misrepresented his client (the "Plaintiff") in a dispute with the tax authorities, causing it to suffer damages estimated at $5.7 million.

The Court found that the Expert Opinion lacked methodology, which prevented the Judge from understanding, accepting and following the expert's opinion3 and that, at best, the Expert Opinion reflected the expert's own standpoint, without adding substance,4 which point of view was expressed without reference to any recognized professional standards, thereby supporting its dismissal.

First, the Court noted what distinguished the Expert Opinion in dispute:

[12] [...] [translation] In this case, it is admitted and clear that the Expert Opinion submitted sets out a legal opinion in tax law by a lawyer specializing in this field [...]


[16] ... [translation] the expert report clearly presents a legal opinion in tax law aimed at demonstrating that the defendant Gadbois failed to make [translation] "appropriate legal representations" to Revenu Québec, an argument related to the "lieu de fourniture/place of supply," based on sections 22.2 to 24.3 of the Act respecting the Québec sales tax(AQST) that the expert qualified as rudimentary.

[Our underlining]

After setting out the framework governing an application for the dismissal of an expert opinion,5 the Judge pointed out that [translation] "as a general rule, 'expert evidence that is legal in nature is inadmissible, as it is of no use to a judge', who is an expert in domestic law."6

To be admissible, expert evidence that is legal in nature must fall outside the experience and knowledge of the judge and provide technical or scientific information.7 On this point, the Judge relied on the principles established by case law—especially regarding the professional practice standards for notaries, architects and lawyers, areas in respect of which the courts can admit expert evidence constituting a legal opinion.8

The Court then proceeded to analyze the content of the Expert Opinion to determine whether the expert report could enlighten the trial judge—more specifically, [translation] "Would a lawyer specializing in tax law have taken the same steps and made the same decisions as the defendant Gadbois?"9 Justice Lucas's conclusion is unequivocal: [translation] "[...]the Expert Opinion would be of no help to the trial judge in answering this question."10

In support of its reasons, the Court began by quoting excerpts from the Expert Opinion, in which the expert appears to offer a personal assessment instead of a technical explanation, excerpts such as: [translation] "rudimentary argument," "[the Defendant's] failure to raise fundamental issues [...] "leaves one dumbfounded" and "a basic rule that any tax expert, and even more so a tax specialist, is supposed to know"11 [Underlining added by Court].

Relying on professional liability case law in related fields, the Court then drew a clear distinction between the substance of the Expert Opinion in dispute and that of the expert evidence previously considered by the courts. The key distinction being: expert evidence that is based on standards and practices and draws on technical knowledge, scientific or technical literature, case law or legal doctrine.12 The Court placed the Expert Opinion in this case at the opposite end of the spectrum, qualifying it as a personal assessment of a peer's work.

After careful consideration, the Court allowed the application for dismissal, despite the requisite caution when ruling on such applications, which often leads a court to defer the issue of the admissibility of expert evidence to the trial judge. The criterion warranting dismissal was therefore met: the expert evidence was prima facie of such little weight or value that its benefits, if any, were clearly outweighed its by prejudicial effects.13

Lawyers providing an expert opinion—even if they practise in a specialized field—are not excused from indicating the usual practices or standards of diligence, otherwise their expert evidence may leave the court dumbfounded!


1. 9125-5265 Québec inc. c Gadbois, 500-17-108877-195 (SC), May 24, 2024. (PDF)

2. Ibid at para 34.

3. Ibid at para 27.

4. Ibid at para 28

5. Ibid at paras 9-11. See Excavations Payette ltée c Ville de Montréal, 2022 QCCA 1393, paras 20 et seq; R v Mohan, [1994] 2 SCR 9; White Burgess Langille lnman v Abbott and Haliburton Co., 2015 SCC 23, [2015] 2 SCR 182 paras 16 et seq.

6. Ibid at para 17.

7. Ibid.

8. Ibid at para 18.

9. Ibid at para 21.

10. Ibid at para 22.

11. Ibid at para 23.

12. Ibid at paras 29–31.

13. Ibid at para 10.

The content of this article is intended to provide a general guide to the subject matter. Specialist advice should be sought about your specific circumstances.

See More Popular Content From

Mondaq uses cookies on this website. By using our website you agree to our use of cookies as set out in our Privacy Policy.

Learn More