In Warner v Smith & Nephew Inc (“Warner”) the majority of the Alberta Court of Appeal held that meeting the procedural requirements for certification trumped concerns regarding the substance of the action. The Court disagreed on whether and to what extent evidence may be considered on a certification motion. The reasons for this are clear (although where the line ought to be drawn is not): the Supreme Court of Canada has directed courts to provide a meaningful screening device on certification by conducting more than a superficial analysis but not an assessment of merits or weighing of the evidence.
Motions to Certify A Class Action
To commence a class proceeding, a plaintiff must make a motion for certification and to appoint the plaintiff as the representative of the class. The proposed representative plaintiff must lead evidence to establish “some basis in fact” for each of the certification requirements (other than the requirement that the pleadings disclose a cause of action).
The evidentiary burden of “some basis in fact” continues to provide fertile ground for arguments on both sides of a proposed class action. The Supreme Court of Canada has established the outer boundaries for consideration of evidence on a certification motion:
- A court must do more than superficially analyze the sufficiency of the evidence –analysis should not amount to “nothing more than symbolic scrutiny” and,
- A court must not determine the merits of the proceeding by assessing or weighing the evidence – the focus is on the form of the action rather than its viability or strength.
These outer boundaries create a tension in certification motions between weighing the evidence too little (or not at all) and weighing the evidence too much.
The Underlying Claim in Warner
In Warner, Ms. Warner sought to certify a class of all persons in Canada who had a particular hip resurfacing system implanted. The hip resurfacing system had two metal contact points, which led to chromium or cobalt ions being released into the blood. In Ms. Warner’s case, years after being implanted with the hip resurfacing system, she was advised that the cobalt ion levels in her blood were considered toxic, and she underwent a further surgery to remove the hip resurfacing system and replace her hip. Ms. Warner later commenced a proposed class action claiming that the system was unsafe as a medical device, not fit for its intended purpose, and not of merchantable quality.
On the certification motion, the judge took seriously the courts’ role in providing a meaningful screening device and primarily declined to grant certification on the basis that the class proceeding was not a preferable procedure. He concluded, based on the evidence on the certification motion including that the long-term health effects of elevated chromium or cobalt ion levels were unknown, that there was little prospect the plaintiff would succeed in the allegation that the hip resurfacing system should not have been available on the market. In addition, there were other litigation procedures available to the plaintiff.
The Court of Appeal’s Majority and Dissenting Reasons in Warner
On appeal, the Court agreed on the procedural focus, test, and evidentiary burden on a certification motion. The Court held that the class ought to be certified (although Slatter JA disagreed that the subclass should be certified) and the certification judge erred when he gave too much weight to the prospective merits of the action.
However, the Court of Appeal disagreed on whether to consider if a plaintiff can prove its claims at the certification stage. Justice Paperny, writing for the majority, emphasized that a certification of the claim does not involve consideration of its merits. It is a procedural motion only. Accordingly, the certification judge’s consideration of whether medical evidence could establish the effects of elevated levels of cobalt or chromium ions was impermissible weighing of the evidence and an impermissible assessment of the merits of the claim.  Justice Paperny was unmoved by the lack of expert evidence establishing toxicity of these ions: “the appellant does not have to establish the strength of her claim at this stage; that is a matter for the trial judge.”
In his dissent, Justice Slatter was troubled by the inability of either side to prove allegations relating to the long-term effects of chromium or cobalt ions in relation to a subclass. The evidence on the record, including from the plaintiff’s medical expert, was that no one knew or had established, scientifically or otherwise, the long-term health effects of these ions. If scientists and doctors could not resolve this issue, Justice Slatter queried whether a trial judge could – any experts called to testify at trial could only answer that “no one really knows” and in the end, neither side would be able to meet the balance of probabilities and the case would be dismissed. Justice Slatter commented:
To be clear, the certification motion is not the place to weigh the expert evidence, but that is not what is happening here. The expert evidence is uncontradicted: no one knows whether the presence of metal ions in the patient is of significant concern. The unsuitability of civil trials for resolving scientific mysteries is one reason that this class proceeding is “not the preferable procedure” for resolving the claim of the subclass who have metal ions in their blood following the [hip resurfacing] procedure.
Justice Slatter concluded that a class proceeding was not the preferable procedure for resolving the “metal ions” subclass claim.
Ongoing Ambiguity on Certification Motions
Warner exemplifies the ongoing ambiguity and tension on certification motions where courts are to provide a meaningful screening device but refrain from assessing the merits of the claim. As Justice Paperny recognized, this can be a fine line and each case must be assessed on its own merits. However, a meaningful screening device requires some consideration of the merits and not simply procedure.
 Ibid at paras 6, 13-18, 28, 37-42, 44.
 Hollick, ibid at para 16; Pro-Sys, supra note 3 at para 99.
 Pro-Sys, ibid at paras 102-103.
 Warner, supra note 1 at paras 1, 2, 20, 46-49, 52-53
 Warner, supra note 1 at paras 13-15, 21, 36-37, 89, 90.
 Ibid at paras 10, 13-17, 36-38.
 Ibid at at para 38.
 Ibid at at para 111.
 Ibid at at para 112
 Ibid at at para 117 (emphasis added). Note that while both the majority and the dissent refer to metal or metallic ions throughout the judgment, this is an overly broad characterization as it appears only chromium or cobalt ions are at issue. Certain metal ions, such as iron, are essential for almost all living organisms and their effects have been extensively studied: see e.g., N. Abbaspour, R. Hurrell and R. Kelishadi, “Review on iron and its importance for human health” (2014) 18:2 J Res Med Sci 164.
 Ibid at para 18.