Evidence - Expert Opinion - RCP 53.05The Rules of Civil Procedure have requirements for expert report to be used in evidence: RCP R53.03.
. Lockyear v. Wawanesa Mutual Insurance Company
In Lockyear v. Wawanesa Mutual Insurance Company (Div Ct, 2021) the Divisional Court the court pointed to the similarity between Rule 53 of the RCP regarding expert reports and R10.2 of the LAT rules:
 What is the rationale behind rule 10.2 of the rules applicable to the Licence Appeal Tribunal? Presumably, it is much the same as the policy behind rule 53.03 (1) of the Rules of Civil Procedure which sets out the requirement for an expert to provide a report and rule 53.03(2.1) which requires, for the matters to which it applies, that such a report outline not only the opinions of the expert but also the basis for them:. Johnson v. Rajanna
In our view, these cases indicate that the "substance" requirement of rule 53.03(1) must be determined in light of the purpose of the rule, which is to facilitate orderly trial preparation by providing opposing parties with adequate notice of opinion evidence to be adduced at trial. Accordingly, an expert report cannot merely state a conclusion. The report must set out the expert's opinion, and the basis for that opinion. There is some flexibility. It is understood that a witness will not be tied strictly to what is said in the report:
Further, while testifying, an expert may explain and amplify what is in his or her report but only on matters that are "latent in" or "touched on" by the report. There are limitations that have been found to apply to rule 53.03 of the Rules of Civil Procedure and should have application to rule 10.2 of the rules applicable to the Licence Appeal Tribunal:
An expert may not testify about matters that open up a new field not mentioned in the report. A judge and in this case the Licence Appeal Tribunal have discretion but the general policy rationale is to ensure that the opposing party is not taken by surprise:
The trial judge must be afforded a certain amount of discretion in applying rule 53.03 with a view to ensuring that a party is not unfairly taken by surprise by expert evidence on a point that would not have been anticipated from a reading of an expert's report. 
In Johnson v. Rajanna (Ont CA, 2021) the Court of Appeal considered the impact of an expert report that was not filed in accordance with R53.03(2.1):
 As to the third factor, the respondents say that the fresh evidence is not credible because Dr. Kellen’s report is not accompanied by an assurance of his objectivity, in the form of an acknowledgment of the expert’s duty (Form 53), signed by Dr. Kellen, as required by r. 53.03(2.1) of the Rules of Civil Procedure, R.R.O. 1990, Reg. 194. Further, they say that Dr. Kellen makes groundless assumptions and assertions about Dr. Rajanna, which should lead this court to conclude he cannot meet his obligation to provide the court with a fair, objective and non-partisan opinion.
 The respondents are correct that the report is not accompanied by a Form 53 and, in portions of his report, Dr. Kellen made certain assumptions which he characterized as “a couple of unsubstantiated theorizations because of large information gaps and things that do not ‘fit’”.
 To the extent there are deficiencies in Dr. Kellen’s report, they may speak to a lack of experience as an expert witness or the preparation of the report without input by counsel. We view them more as deficiencies that go to the fourth Palmer factor, and that could prove fatal if not rectified before trial or a further summary judgment motion. Nonetheless, in our view, Dr. Kellen’s evidence is reasonably capable of belief.
 Turning to the fourth Palmer factor, the respondents argue that Dr. Kellen’s report suffers from a further, fundamental deficiency: it fails to definitively opine on both standard of care and causation. Dr. Kellen could have expressed his opinions with greater clarity. But, contrary to the respondents’ assertion, his opinions, summarized above, address both standard of care and causation.
 In our view, if the motion judge had the benefit of Dr. Kellen’s affidavit and report he would not have granted summary judgment in favour of the respondents.