Executive Summary: Key Legal and Evidentiary Issues

• Certification was sought for a class action alleging Bayer’s failure to adequately warn about the risk of migration associated with the Mirena intrauterine device.

• The primary legal issue concerned whether Bayer’s product monograph before 2014 sufficiently disclosed the risk of migration, and whether this omission constituted a breach of the duty to warn.

• The claim for unjust enrichment was found to be fundamentally flawed and not certifiable, while the duty to warn claim was permitted to proceed with leave to amend.

• The class definition was narrowed to women who used Mirena, experienced migration, and claimed damages as a result.

• Common issues certified included Bayer’s duty to warn, its knowledge of risks, and the sufficiency of warnings, with punitive damages also certified as a class-wide issue.

• Ms. Todd was found to be an adequate representative plaintiff, and a strict litigation plan was ordered to ensure timely progress of the case.

Facts of the case

Elizabeth Todd, as the proposed representative plaintiff, applied to certify a class action against Bayer Inc. regarding the Mirena intrauterine contraceptive device. Mirena, manufactured by Bayer, is inserted into the uterus and releases a synthetic form of the hormone progesterone (levonorgesterel). It is approved by Health Canada as a drug for contraception for up to five years and for the treatment of idiopathic menorrhagia. The case did not concern whether Mirena was safe, but whether Bayer disclosed all risks associated with Mirena in the product monographs used in Canada from its initial sale in the early 2000s until 2014, when the wording was changed to describe the risk of migration of the device outside the uterus.

Ms. Todd alleged that Bayer had a duty to warn prospective users and their doctors of the potential risk of migration, and that Bayer failed to do so when it should have known better. She relied, among other things, on the wording of the Mirena product monograph used in the United States from 2008 onwards, which identified migration as a risk. Bayer argued that certification was inappropriate for several reasons, including alleged deficiencies in the pleading of causes of action, an overly broad proposed class definition, predominance of individual issues, and that Ms. Todd was not an appropriate plaintiff.

Discussion of policy terms and clauses at issue

The case focused on the adequacy of the product monograph, a factual and scientific document required by Health Canada to describe a drug’s properties, claims, indications, and risks. The plaintiff asserted that the Canadian monograph prior to 2014 failed to adequately disclose the risk of migration, as it only mentioned “perforation.” Expert evidence was presented by both parties: Dr. Katia Betito opined that the use of “perforation” was insufficient to disclose the risk of migration, while Dr. Waddington, Bayer’s expert, asserted that healthcare professionals would understand “perforation” to include migration. The court found that the interpretation of the product monograph and what language was required to communicate risk to healthcare professionals was an issue for trial.

Bayer’s argument that Health Canada’s approval of the product monograph absolved it of responsibility was rejected; compliance with Health Canada is relevant but not determinative of liability at common law. The sufficiency of the warning is to be judged by an objective standard and can be assessed on a class-wide basis.

Certification and class definition

The court applied the test for certification under the Class Proceedings Act, SA 2003, c C-16.5, s 5(1). The unjust enrichment claim was found to have a “radical defect” and could not be certified, as the sale of Mirena constituted a juristic reason for Bayer’s enrichment. Claims based on statutory breaches were found to be abandoned and not certified.

The class definition was amended during oral argument to: “All women throughout Canada who used Mirena during the Class Period and who experienced migration and claim damages as a result as well as their estates, administrators or other legal representatives.” The court declined to restrict the class period to 2008–2014, noting that the timing of Bayer’s knowledge of the risk was a matter for discovery.

Common issues and representative plaintiff

The court certified common issues relating to whether Mirena is prone to migrate, Bayer’s awareness of migration risk, the existence and breach of a duty to warn, and whether punitive damages should be assessed on a class-wide basis. Issues relating to unjust enrichment, special damages, and subrogated health care costs were not certified.

Ms. Todd was found to be an adequate representative plaintiff. The court found that her reliance on her doctor, and not reading the product monograph herself, was consistent with the learned intermediary rule. The fact that she had not read all affidavits or the product monograph did not disqualify her, as counsel could summarize and interpret materials for her.

Ruling and outcome

The proceeding was certified as a class action according to the parameters set out in the reasons. Ms. Todd was granted leave to amend her pleading to address deficiencies, and both parties were ordered to submit a litigation plan with deadlines to ensure the case would be trial-ready within 24 months of the issuance of the reasons. The successful party at this stage was the applicant, Ms. Todd, as the class action was certified. No specific monetary amount was determined at this stage; any amount to be awarded will be determined at trial following resolution of the common and individual issues.