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Experts and Settlement Proposals Don’t Mix

By Cameron Allan

A recent decision from the Ontario Superior Court of Justice serves as a reminder for counsel to carefully consider the types of documents being provided to their expert witnesses for the preparation of expert reports.

In Simmermon v. Djoudad et. al., 2024 ONSC 2388, a motion judge struck an expert report from the evidentiary record prior to an application hearing, on the grounds that the expert’s report was biased and could expose the application judge to litigation-privileged information.


The applicant sought an order requiring the respondents to make structural changes to their backyard in order to allow the applicant to safely manoeuvre and park her vehicle in her duplex’s backyard. The applicant and respondents lived at two separate properties where the only available parking was located in the backyards of the respective properties. The applicant required a right of way through the respondent’s backyard in order to access her backyard parking.

In support of her application, the applicant filed two expert reports, one of which was from Jerrold Corush. Mr. Corush was retained by the applicant to provide an expert opinion and a technical assessment of the right of way. He assessed the design options, and was asked to make recommendations regarding potential backyard-layouts that would allow the applicant and respondents to park their vehicles all year round without the applicant’s vehicle becoming obstructed.

The Corush Evidence

Mr. Corush authored a report dated September 14, 2022.  In his report, he refers to a legal proposal as “Solution #1”, which proposed the removal of all structures on the right of way as a potential solution. “Solution #1” happened to mirror a proposal made by the applicant’s counsel in a demand letter, dated September 20, 2021.  

Mr. Corush’s report went on to discuss a “legal counterproposal”. The counterproposal consisted of a proposal made my respondent’s counsel in correspondence dated October 15, 2021. Mr. Corush’s report opined that the respondent’s counterproposal did not meet the vehicle access requirements necessary for the applicant, based on his technical expertise.

Mr. Corush’s report went on to recommend the removal of a spruce tree, a maple tree, plant beds and fence segments along the right of way. His report was accompanied by his CV and an acknowledgement of expert’s duty pursuant to Rule53.03 of the Rules of Civil Procedure.

The respondents refused the first two proposals and put forward two of their own expert reports. The applicant then asked Mr. Corush to provide a third solution that would not require the removal of the maple tree. Mr. Corush proposed Solution 3, which would entail the removal of a plant bed, the spruce tree and fence segments.

Mr. Corush was examined under oath on July 19, 2023. In an undertaking made during the examination, Mr. Corush was asked to provide copies of the documents that the applicant’s counsel had provided him with for use in developing his proposals 1-3. Mr. Corush’s answer to the undertaking revealed that he was provided with and relied upon numerous “without prejudice” correspondence sent between applicant’s counsel respondents’ counsel.

The correspondence contained various proposals and counterproposals communicated by the parties’ lawyers. Another document reviewed by Mr. Corush was the respondents’ Rule 49 offer, which included two counter proposals. Much of the evidence Mr. Corush gave in his report and affidavit were in response to proposals put forward by the respondents’ counsel.

Prior to the hearing of the application, the respondents brought a motion seeking to strike the expert report and affidavit of Mr. Corush, amongst other remedies, on the grounds that he was not a fair, objective, and non-partisan expert witness as required by Rule 4.1.01(1).

Legal Framework:

Rule 53.03 sets out the requirements for expert reports. In particular, Rule 53.03(2.1) states that an expert report must contain the following information:

The expert’s reasons for his or her opinion, including,

i. a description of the factual assumptions on which the opinion is based,

ii. a description of any research conducted by the expert that led him or her to form the opinion, and

iii. a list of every document, if any, relied on by the expert in forming the opinion.


An acknowledgement of expert’s duty (Form 53) signed by the expert.

The motion judge considered the legal test for admissibility of expert evidence as set out in Parliament et al. v. Conley and Park, 2019 ONSC 3995:

 [10]              In the first stage, as articulated by the Supreme Court in R. v. Mohan1994 CanLII 80 (SCC), [1994] 2 S.C.R. 9, the proponent of the evidence must persuade the trial judge that the proposed expert opinion is:

i.         relevant;

ii.         necessary;

iii.         not barred by any other exclusionary rule; and 

iv.         given by a properly qualified expert.  

[11]           In the second stage, the trial judge must engage in a gatekeeping function in which the trial judge balances the potential risks and benefits of admitting the evidence to determine whether the potential benefits justify the risks: White Burgess at para. 24.

Justice Doyle also cited Bruff-Murphy v. Gunawardena, 2017 ONCA 502, which defines the appropriate role of experts at paragraph 52:

Experts should not become advocates for the party by whom they are retained. To be of assistance to the trier of fact, an expert must remain objective and their function is to provide the trier of fact with expert opinion evidence that is fair, objective, and non-partisan

Where the expert crosses the boundary of acceptable conduct and descends into the fray as a partisan advocate, the trial judge is required to fulfil her ongoing gatekeeper function and exclude in whole or in part the expert’s unacceptable testimony.

The Court’s Findings:

Justice Doyle determined that Mr. Corush’s evidence raised concerns at the first stage of the test set out in R v. Mohan. The judge found that the expert evidence may be barred by an exclusionary rule due to the fact that the expert has been exposed to settlement offers, giving rise to the issue of bias. There was significant concern that the expert had been exposed to litigation privileged information and was, thus, made aware of the responding party’s litigation strategy.

In addition to consideration of the Mohan test, the judge also utilized the Court’s gatekeeping function by balancing the potential risks and benefits of admitting Mr. Corush’s evidence.  Justice Doyle found that the evidence provided little probative value, as the application judge could consider the various backyard proposals for the right of way without the expert’s evidence.

The prejudicial effect of the evidence was significant given Mr. Corush’s exposure to litigation privileged information. Mr. Corush’s exposure to litigation privileged information meant that his expert opinion could not be considered impartial. Once Mr. Corush was asked to comment on and criticize the respondent’s proposals, he stepped into the role of the applicant’s advocate, and “entered into the fray of litigation strategy”[1]. Further, the application judge would have been exposed to the privileged settlement offers and discussion through Mr. Corush’s evidence.

In a further blow to the applicant, the motion judge found that the applicant had failed to comply with Rule 53.03(2.1) when it refused to provide the instruction letter given to Mr. Corush, as is mandated. (see Moore v. Getahun, 2015 ONCA 55).

Ultimately, Justice Doyle struck and removed the evidence of Mr. Corush from the application record.

[1] At para 98.