Evidence - Expert Duties of Impartiality and Independence (2). Ontario (Natural Resources and Forestry) v. Town of South Bruce Peninsula
In Ontario (Natural Resources and Forestry) v. Town of South Bruce Peninsula (Ont CA, 2022) two judges (of three) of the Court of Appeal agree on the following comments regarding employed expert witnesses in this environmental POA prosecution case:
The Governing Principles Relating to Employee Experts as Witnesses
 The threshold test for the admission of expert evidence is that: the evidence must be relevant; it must be necessary in assisting the trier of fact; no other evidentiary rule should apply to exclude it; and the expert must be properly qualified: R. v. Mohan and R. v. Abbey. These threshold requirements apply to employee experts. Apart from the issue of qualification, they are not at issue in this appeal.
 One aspect of proper qualification is the assessment of whether the witness has a disabling bias or lack of independence that renders the witness unable or unwilling to provide fair, non-partisan and objective assistance to the court.
 Three concepts underlie an expert’s duty to the court: impartiality, independence, and absence of bias. This court summarized and paraphrased these White Burgess principles in Mills: “Experts are expected to be (a) impartial, in the sense that they give only an ‘objective assessment of the questions at hand’; (b) independent, in the sense that their opinions result from an exercise of ‘independent judgment, uninfluenced by who has retained’ them or the ‘outcome of the litigation’; and (c) unbiased, in the sense that they do not ‘unfairly favour one party's position over another’”. The court added: “The acid test is whether the expert's opinion would not change regardless of which party retained him or her.”
 A trial judge’s assessment of a witness’s ability to provide fair, non-partisan and objective assistance to the court arises three times in the course of a trial. First, the trial judge addresses the issue in qualifying the witness to testify.
 The procedure prescribed by White Burgess calls on the expert to attest that his or her duty to assist the court overrides any obligation to the party calling the expert as a witness. Then: “the burden is on the party opposing the admission of the evidence to show that there is a realistic concern that the expert's evidence should not be received because the expert is unable and/or unwilling to comply with that duty.” But, “the burden to establish on a balance of probabilities this aspect of the admissibility threshold remains on the party proposing to call the evidence.” Where the evidence falls short, the witness can be disqualified, “or those parts of it that are tainted by a lack of independence or impartiality, should be excluded.”
 I make two observations about the qualification process. First, testimonial qualification is determined in a voir dire with the proponent tendering the witness, the opponent cross-examining, and the judge deciding. The onus throughout the qualification process is on the proponent and the admissibility standard is on the balance of probabilities.
 Second, perfectly impeccable impartiality or independence is rarely possible and is not the standard. In White Burgess, Cromwell J. explained that: “This threshold requirement is not particularly onerous and it will likely be quite rare that a proposed expert's evidence would be ruled inadmissible for failing to meet it.” He added this comment: “I emphasize that exclusion at the threshold stage of the analysis should occur only in very clear cases”. Deficiencies that are not disqualifying can be accounted for by imposing limits on the witness’s evidence and in weighing the evidence.
 This rarity usually leads counsel away from a full blown effort to disqualify a witness. The voir dire is perfunctory, if it happens at all, once qualifications have been accepted and the parameters of the expert evidence are set. Instead, the focus is on showing through cross-examination on the merits of the opinion that the witness has a measure of partiality that must be discounted in weighing the evidence.
 The second time the trial judge assesses a witness’s ability to provide fair, non-partisan and objective assistance to the court is during cross-examination. The trial judge’s gatekeeping function is never relaxed. This court held in Bruff-Murphy, that even if the expert is permitted to give evidence, the judge must continue to “fulfill his [or her] ongoing gatekeeper function and exclude in whole or in part the expert’s unacceptable testimony.” Hourigan J.A. noted that “the court has residual discretion [under this ongoing gatekeeper function] to exclude expert evidence even after admitting it, if later in the trial prejudice emerges that was not apparent at the time of admission.” As in Bruff-Murphy, the disabling bias may only emerge in cross examination on the merits and result in disqualification. This too is a rare event.
 The third time is when the trial judge weighs the expert’s evidence. Bias that is not disabling is treated as a question of weight, as this court observed in Alfano v. Piersanti :
Typically, when such an attack is mounted, the court will admit the evidence and weigh it in light of the independence concerns. Generally, admitting the evidence will not only be the path of least resistance, but also accord with common sense and efficiency. The assessment of an employee expert witness’s impartiality and independence is case-specific. The caselaw provides guidance and has yielded several factors that better specify the test beyond the governing principles. It is clear that an employment relationship is not a sufficient basis for finding that the witness lacks testimonial independence or is biased. The area that has posed the most difficulties is where the expert employee had some involvement in the prosecution’s case. The deeper that involvement, the more likely the witness is to be disqualified as lacking the necessary degree of impartiality and independence, as the cases show.
 It is possible to make some useful analytical distinctions. Consider that an event causes an investigation, which leads to a decision to prosecute, and then to the prosecution itself. Each of these three stages has unique pressures. For explanatory convenience I address each, but deal last with the decision to prosecute.
Involvement in the Investigation
 The expert’s involvement in the investigation is not necessarily disqualifying. This is seen in many regulatory or quasi- criminal cases, which start with an event that is then investigated. In regulatory prosecutions, as this case among others shows, an expert opinion is necessary before charges are laid because causation is critical, might not be obvious, and might well be innocent. It would be impossible, where technical or scientific issues are engaged, for a prosecutor who is not expert in the field to evaluate the reasonable prospect of conviction without one or more expert opinions.
 For example, in Live Nation, the employed engineers were among the first on the scene in a Ministry of Labour investigation. Their investigation was technical and yielded information necessary to determine the physical cause of the collapse. They were not under the direction of the lead investigator on the prosecution. They were permitted to testify, with any concerns going to weight.
 Any expert must do some investigation or get investigation data in order to proffer an opinion. As Nakatsuru J. observed in Live Nation, the argument that “a proper expert should be one who is retained only after the investigation is complete, is handed a brief of the fruits of the investigation, and then testifies by giving an opinion based on a hypothetical or upon the work done by others” is unrealistic. There is nothing untoward in the employee experts “observing the scene, conducting interviews, and performing testing”.
 In Tang, a forensic accountant employed by the Ontario Securities Commission was found not to be disqualified even though his regulatory investigation led to the criminal charges. His investigative work for the Commission did not prevent him “from giving any and all forensic accounting evidence in the criminal proceeding”. He gave evidence as to tracing the funds, to which the issue of criminal guilt was only tangentially related. The court noted:
The determination of whether an expert's prior connection with an investigation should disqualify that person from giving expert opinion evidence can only be made within the full context of the specific facts. The nature of the prior investigation, the role played by the individual expert in that investigation, and the nature of the proposed expert evidence would all be important considerations in the determination of whether the expert's prior involvement made the case…one of those relatively rare cases in which an expert's lack of independence or impartiality provided a basis for holding that the expert was not competent to testify. I now move to the other end of the spectrum from the employee expert’s involvement in the investigation to involvement in the prosecution itself.
Involvement in the Prosecution
 Involvement in the prosecution itself requires closer scrutiny than involvement in the investigation because employee experts participating in the prosecution present the risk of becoming advocates for the prosecution.
 In McManus, an officer was involved in drug investigations and received information about the accused over a period of four years. He participated in the execution of a search warrant, testified at the bail hearing, and, in response to comments of the preliminary inquiry justice, produced, on his own initiative, an expert report that strengthened the prosecution's case. This court held that the history established a lack of independence, so that the jury should not have heard the officer’s opinion. Recently retired Justice David Watt extracted this principle from McManus, with which I agree:
An interest in or connection with the litigation does not automatically render the proposed expert evidence inadmissible. However, a court must consider whether an expert's relationship to or interest in the litigation would result in the witness being unable or unwilling to carry out their primary duty to provide fair, non-partisan and objective assistance to the court. A heightened concern occurs for police expert witnesses to ensure their ability to offer impartial expert evidence. Livingston did not involve an employee but engaged similar issues. The trial judge did not qualify a retired police officer, who was an expert in the forensic recovery, examination and interpretation of computer data. The trial judge noted, that the proposed expert: “took on an extensive, active and at times a proactive role in the investigation [, and] provided investigators with strategic and legal advice in their efforts to mount a case against the defendants.” After an extensive review of the evidence, the trial judge declined to qualify the witness:
Taking into consideration the nature and extent of Mr. Gagnon’s long and extensive participation in the police investigation of the defendants, as well his email comments revealing bias, I am satisfied there is a realistic concern that he is unable to provide independent, impartial and unbiased evidence. In Advanced Construction, the employee was an engineer. He was “himself investigating directly by his observations of the information accessible to him and he was assisting the investigators by being the contact person with the technical knowledge beyond the expertise of the lead investigator”. He was in “constant contact” with the lead investigator, who could not interpret the evidence without his assistance. He also retained the external expert but did not give pertinent information to him until the trial, when in doing so, he breached the witness-exclusion ruling. Knazan J. decided that he would permit the expert to give evidence on all aspects of engineering and geotechnical engineering, but not on the root causes of the collapse of the rig that led to the charges. He found that the witness “identifie[d] too closely with the prosecution to be able give an impartial opinion.”
 In Live Nation, the employed experts sat in on suspect interviews. Nakatsuru J. found that this raised a “red flag”. However, they testified that they had suspended professional engineering judgment until all the facts were in. He permitted them to give evidence without limitations.
 The degree of involvement can be mitigated by the expert’s approach to informing himself or herself about the facts on which the opinion is sought. In Tesfai the trial judge allowed a police officer to give opinion evidence relating to drug trafficking. Trafford J. noted:
Detective Sergeant Babiar testified about the procedures he followed to ensure the impartiality of his opinion in this case. He was approached by some of the senior officers in connection with a possible involvement in Project Marvel. They provided him with an overview of the project, in general terms. Once he agreed to join the investigation, the IPCs to be considered by him were selected by the Crown, and sent to him electronically. He received some surveillance folders, arrest folders and other information in some other folders. He also received an audiorecording of the calls and some transcripts. However, he did not pay any attention to this information, other than to open it and close it, so that he knew it related to this assignment. He did not consider the affidavits to obtain the two authorizations in the project. His first step was to read all of the calls, independently of anyone else's input. He did not read anything else. He did not have any theory of the Crown to guide him, because it could affect his analysis of the conversations. He did not want any information that might bias him in his review of the pertinent words in the pertinent calls.The officer was permitted to testify as an expert.
 In T.A., the Crown wished to call an officer to explain coded and street language in wiretaps connected to a robbery. The trial judge found:
The officer listened to wires as the project was ongoing and works in the same building as the officers directly involved in the investigation. He testified, however, that he did not proffer an opinion before charges were laid, he was not involved in the laying of charges, and he did not discuss his analysis of the wires with other officers involved in the project. I find that there is no realistic concern that this particular officer will not be able to execute his duty fairly and impartially. I turn now to the issue of the employee expert’s involvement in the decision to prosecute.