I have written about the doubts that I and others have about the increased reliance of Canadian courts on social science evidence in rights litigation. A recent decision of the Supreme Court of Nova Scotia, Trinity Western University v. Nova Scotia Barristers’ Society, 2014 NSSC 395, seems to me to suggest that to some judges, at least, this “empirical turn,” as it’s been described, does not come quite naturally.
The University has applied for judicial review of the Barristers’ Society decision to require it to abandon the “covenant” it imposes on its students, which among other things prevents them from engaging in sex outside a heterosexual marriage, before recognizing its law school’s degrees. The application has not yet been heard on the merits. In the meantime, the University has applied to strike parts of affidavits submitted by the Society’s witnesses, on the basis that they contained “material that amounts to a submission, plea or argument. The concern would be that the arguments might be accorded more weight or deference by virtue of their being sworn and in a report of an expert. Expert opinion and argument can be confused.” 
As Justice Campbell explains, these affidavits, despite their ostensible form, “are essentially reports intended to provide expert opinion,”  one of them on “the history of discrimination against gays, lesbians and other sexual minorities, the effect of exclusion on sexual minorities and the role that the state has taken in combatting that discrimination”  and the other on “the effects of the [University’s] covenant on sexual minorities” and “the impact on recruiting sexual minorities if the [Society] were to recognize degrees from [the University’s] proposed law school.” 
Justice Campbell’s explanation of the differences between this evidence and that which courts are used to is worth quoting at length:
 These affidavits, as evidence, occupy a grey area. Affidavits are intended to be statements of facts. They do not contain opinions about evidence or speculation about what evidence could be. But expert reports are intended to convey an opinion based on assumed facts using specialized knowledge, training or experience. These are both affidavits and expert reports. Strictly applying the rules that pertain to affidavits would be impractical.
 Reading through the affidavits gives a sense of just how different they are from the usual, sometimes rather dry, recitation of facts found in an affidavit. They clearly contain information that is not within the personal knowledge of the affiant. Of course they contain opinions. They also include statements that are intended to persuade.
 They are also a departure from what might normally be expected in an expert report. It’s a bit hard at times to differentiate between conclusions based on expertise, assertions of facts, and advocacy. The reports contain statements about historical events and trends that are supported by their assertion with no intent that they be subject to formal proof.
 The language used is at times powerful. It is at times impenetrably academic. And, at other times takes the form of advocacy. One is not left in any doubt at all about whether these experts have a definite view about what the outcome of the matter should be. … That isn’t what an expert opinion has traditionally sounded like. It isn’t what affidavits have traditionally sounded like either.
 Technically, a report of an expert would contain a statement of assumed facts that would have to be proven in court. The expert would then offer an opinion or a theory relevant to the case, using training, knowledge and expertise of a kind not possessed by the judge. That opinion would be based on those assumed and to be proven facts. That opinion would be testable or verifiable.
 Charter litigation has changed that.
 Social science evidence is critical in making decisions on the interpretation of the Charter especially when those matters involve public policy. Reports from experts in those areas convey a kind of information that may be quite different. The way in which those reports are used by courts can also be quite different. Adjudicative facts are those that are proven by evidence and relate directly to the subject matter of the proceeding. Judges can take judicial notice of facts that are widely known and beyond dispute. Social science evidence or legislative facts fall between those more traditional categories.
 The Supreme Court has noted that when social and legislative facts are put before a trial judge he or she has to “evaluate and weigh that evidence in order to arrive at the conclusions of fact necessary to decide the case”. The trial judge can be involved in a time consuming exercise of reviewing material and reconciling differences between the experts, studies and research results. Social and legislative facts are also intertwined with adjudicative facts. The judge has to analyze and give appropriate weight to the evidence in its different forms.
 Social science evidence is presented through expert witnesses. The assessment of that evidence relies heavily on the trial judge. Social science evidence will necessarily be different from the reports of experts in the natural sciences. In those areas, where there are controlled experiments, testable predictions, and quantifiable data an expert opinion will usually involve the application of rigorous testing methods. There is no hierarchy of sciences and social sciences are no less rigorous than natural sciences. That statement itself could be the subject further debate requiring expert opinion. Suffice it to say, social sciences and natural science are just different.
 A trial judge has to consider the reliability of the particular social science evidence. If the report goes beyond the scope of the expertise of the writer, that has to be considered. If it is tendentious, or argumentative, or unbalanced those are considerations as well. Social science evidence that is supported by empirical research may be given different consideration from that which is based on anecdotal observation.
To dispose of the University’s motion, Justice Campbell applied a two-part test developed by Justice Doherty, of the Court of Appeal for Ontario, in R. v. Abbey, 2009 ONCA 624, for the admissibility of such evidence. As he described it,
 … First, the party who puts forward the evidence has to show the existence of some preconditions to the admissibility of expert evidence. The proposed witness must actually be an expert. The opinion has to relate to a subject matter that is properly the subject of expert evidence. The opinion has to be logically relevant to a material issue. Finally, the opinion must not “run afoul of any exclusionary rule apart entirely from the expert opinion rule”. …
 Second, if the trial judge decides that the expert evidence meets the preconditions of admissibility, the issue is whether it’s sufficiently beneficial to the trial process to warrant its admission. That involves a discretionary cost-benefit analysis. The “costs” in that analysis are “a consumption of time, prejudice, and confusion.” The benefits are found in the potential value of the evidence to actually prove something of significance. Whether the expert evidence does indeed have that potential requires a consideration of the reliability of the evidence. Reliability can be assessed by considering the subject matter of the evidence, the methodology used by the expert, the expert’s expertise and the extent to which the expert is shown to be impartial and objective.
Reviewing the affidavits in detail, Justice Campbell rejected most of the University’s concerns. However, he observed that one of them contained “parts … that amount to commentary on the current state of Canadian society, politics and public opinion,”  and the other “advocacy on the very matter before the court … openly and unapologetically argumentative.”  Nevertheless, he refused to strike any part of the affidavits, holding that “[t]he elements of argument contained in both involve the kind of prejudice that can be minimized by acknowledging them for what they are.”  Justice Campbell added that it was better to let the merits judge see the “report” ― he regularly referred to the purported affidavits in that way ― in its entirety, in effect suggesting, it seems to me, that these argumentative parts might cause the judge to discount the weight to be given to the affidavits’ conclusion.
This slightly subversive conclusion is probably right. Yet it also suggests that my and others’ worries about the “empirical turn” are not groundless. As I explained here, I do not believe we should renounce any and all resort to social science evidence. But as Justice Campbell makes clear, this evidence is quite different from what judges, especially trial judges, are used to. It almost inevitably contains advocacy, backed by an expert’s aura of credibility on topics judges are likely not be well-versed in. Judges need to pay attention to research methods and weigh the reliability of the studies put before them, but how many of them are trained to do so? Arguably, it would be useful to have some guidelines on dealing with such evidence laid down by appellate courts, but since the Supreme Court held, in Canada (Attorney General) v. Bedford, 2013 SCC 72,  3 S.C.R. 1101, that they must defer to the trial judges’ findings, they are not really in a position to do so. In short, as I have already suggested, the “empirical turn” could well take us off course.