British Columbia Grapples With Evidentiary Issues and the Requirement for a Workable Methodology

Written By Ashley Paterson and Julien Sicco

The evidentiary burden on plaintiffs to have a case certified­—i.e., the “some basis in fact” standard—has been described as a “low bar” in countless cases. Plaintiffs cite the “low bar” in trying to certify their cases, and defendants respond with their own favourable quotes from the case law, noting that this evidentiary burden is not “merely a speed bump” and that the evidence required to support certification must be subject to something more than “superficial scrutiny”.

Last year, two cases in the Supreme Court of British Columbia provided clarity with respect to the evidentiary standards for certifying personal injury product liability cases.

In Bosco v Mentor Worldwide LLC, 2024 BCSC 1931 (Bosco), the Court refused to certify the plaintiffs' class action because the plaintiffs' evidence ought to be given little weight or was inadmissible (generally or for the specific purpose for which it was being used). By contrast, in Ennis v Johnson & Johnson, 2024 BCSC 1759 (Ennis), the Court certified the plaintiff's class action because the plaintiff's evidence was admissible and, though potentially flawed, capable of grounding a methodology to demonstrate the required causal link. Together, these cases shed light on what evidence will (or will not) support certification.

Bosco v Mentor Worldwide LLC

Bosco was a proposed class action brought on behalf of individuals in Canada that had been implanted with silicone breast implants allegedly containing “toxins” that caused connective tissue disorders and various autoimmune symptoms.

The defendants agreed to certify certain of the common issues but opposed certification of the remaining common issues on the basis that the plaintiffs had not produced any evidence to establish that the alleged toxins were present in sufficient quantities to cause adverse health effects. The Court agreed with the defendants and refused to certify the contested common issues.

The Court found that the plaintiffs’ expert evidence was inadmissible because the plaintiffs’ expert had opined on matters that were beyond the scope of his expertise. In particular, the expert's report discussed potential platinum toxicity in silicone implants and the need for further long-term studies even though the expert had not conducted any research on platinum, had not reviewed key documents from another expert's report, and was not aware of any data indicating that long-term exposure to platinum in implants leads to adverse health effects.

The Court also found that a document published by the FDA that provided non-binding recommendations on the format and content of labelling information for manufacturers of silicone breast implants, which Mentor argued was inadmissible hearsay, was only admissible as evidence that the FDA made these recommendations, and was not admissible as evidence that the alleged toxins could cause adverse health effects.

Finally, the Court found that the results of a hair element analysis of an anonymous individual who claimed to have developed the illness due to her implants were admissible but to be given little weight because they were not accompanied by expert evidence to confirm the reliability of the testing methods or to help with the interpretation of the test results.

Ennis v Johnson & Johnson

In Ennis, the plaintiff sought to certify a class action on behalf of individuals in Canada (excluding Quebec) who used talc powder and developed epithelial ovarian cancer. This was the plaintiff’s second attempt to certify the case. The plaintiff had previously tried to certify a broader case on behalf of individuals with a variety of ovarian cancers, but the Court refused to certify it because the plaintiff had not produced sufficient evidence linking talc powder to those cancers. Despite this, the Court granted the plaintiff leave to obtain more evidence and to narrow the class accordingly.

The plaintiff returned to court in 2024 with a narrower class and more evidence to demonstrate a causal link between talc powder and epithelial ovarian cancer. Among other things, the plaintiff relied on expert evidence from Dr. Cramer (an epidemiologist and gynecologist from Harvard) to establish this causal link. In short, the plaintiff’s reformulated certification application was successful. The Court found that her new evidence was sufficient to meet the "very low bar" necessary at certification.

In response to Dr. Cramer's evidence, the defendants pointed to their own expert evidence, which indicated that there were types of epithelial ovarian cancer that were not causally linked to talc powder. The defendants also argued that Dr. Cramer's proposed methodology for establishing the causal link would be dominated by individual issues, like personal histories and histological factors, rather than by common issues. However, the Court refused to weigh the conflicting expert evidence at the certification stage and instructed the plaintiff to rephrase the common question to exclude epithelial ovarian cancers that are not linked to talc.

The defendants also highlighted that Dr. Cramer's methodology did not use the benchmark odds ratio of 2.0 to show the alleged causal link (instead using an odds ratio of 1.29 that accounted for a wide range of individual factors), but the Court still held that, in theory, this methodology could establish a general association between talc powder and epithelial ovarian cancers. The Court was also persuaded by a screening assessment of talc published by Health Canada, which found that “inhaling loose talc powders and using certain products containing talc in the female genital area may be harmful to human health.”

Looking Forward

The Supreme Court of British Columbia’s decisions in Bosco and Ennis illustrate the importance of focused, sufficient and admissible evidence.

In Bosco, the Court refused to certify the plaintiffs' class action on the basis that there was insufficient evidence to establish that the alleged toxins were present in sufficient quantities to cause adverse health effects because the plaintiffs' evidence in this regard was either inadmissible or given limited weight. In Ennis, the Court certified the plaintiff's class action (albeit, on the second try) on the basis of admissible evidence that provided a workable methodology for establishing general causation on a class-wide basis.

Looking forward to 2025 and beyond, we expect the Supreme Court of British Columbia to continue its close look at the evidence filed in support of certification. The so-called “low bar” for certification is a bar nonetheless, and BCSC appears to be prepared to perform more than superficial scrutiny on the evidence filed in support of certification.

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