The perils of overgeneralized proposed common issues, as clarified by the Ontario Superior Court

Blue staircase

The Ontario Superior Court’s ruling in Price v. H. Lundbeck A/S, 2022 ONSC 7160 (Price) highlights the perils of over-generalized “failure to warn” allegations in the context of formulating common issues for the purposes of a proposed class proceeding. In particular, Justice Glustein’s findings in Price remind plaintiffs of the necessity to articulate sufficiently narrow and appropriately specific proposed common issues for certification. This is welcome news for defendants to putative class actions, insofar as it reaffirms the obligations of plaintiffs to clearly articulate the case that has to be met.

Factual background

This certification motion arose in the context of an allegation by the plaintiffs, Jennifer Price and her son, Matthew Janzic, that the anti-depressant drug Celexa® is a “teratogen” that causes congenital malfunctions through its active ingredient, citalopram. It was alleged that a teratogen is an agent that can, under reasonable circumstances of exposure, disturb the development of an embryo or fetus and thereby cause congenital malformations.

The plaintiffs brought the action against H. Lundbeck A/S and Lundbeck Canada Inc., who they allege manufactured, distributed and marketed Celexa®. However, rather than seeking to certify a common issue related to general causation (linking Celexa® to any particular congenital malformation) or the defendants’ alleged failure to warn of such a causal link, the plaintiffs proposed the following common issue: “From 1999, did the defendants breach their duty to warn Canadian physicians and patients that Celexa® is or may be teratogenic?” (the Proposed Common Issue).

Procedural history

The proceeding dated back to December 2014, following which the Proposed Common Issue underwent an evolution before the formulation presented to Justice Glustein. At the original certification hearing , the plaintiffs initially proposed two common issues: (1) is citalopram or may citalopram be teratogenic; and, if so, (2) did the defendants breach a duty to warn Canadian physicians and patients that citalopram is or may be teratogenic. After receiving the defendants’ materials, the plaintiffs subsequently abandoned the first issue and focused their efforts on the duty to warn angle.

Despite this revision, Justice Perell nonetheless initially denied certification, concluding that: (i) the alleged “failure to warn” did not meet the commonality requirement, and (ii) even if it did, a class action would not be the preferable procedure.

Justice Perell’s findings were subsequently appealed and overturned. In that decision, the Divisional Court found that the failure to warn issue advanced by the plaintiffs “always contained an aspect of causation despite counsel’s concession.” The Divisional Court did not make a determination about whether the “duty to warn causation issue” (i.e., the Proposed Common Issue ultimately presented in the Price decision before Justice Glustein) satisfied the conditions for certification under the Class Proceedings Act, 1992 (the CPA). Accordingly, it was ordered that the certification motion be reheard by a different judge.


Once remanded back to the Superior Court, Justice Glustein considered the two-staged nature of the Proposed Common Issue as it was framed by the plaintiffs:

  1. The “general causation” proposed common issue of whether Celexa® is or may be teratogenic, and, if so,
  2. The “duty to warn” proposed common issue of whether the defendants breached their duty to warn Canadian physicians and patients of that teratogenicity.

After providing an overview of the applicable law on the test for certification, Justice Glustein considered the objections that the defendants raised in response to the PCI pursuant to sections 5(1)(c) and (d) of the CPA.

In considering the first aspect of the Proposed Common Issue, relating to causation, the Court found that the issue, as it was framed, could not possibly and sufficiently advance the litigation, even if answered in the affirmative. This is because liability could only properly exist if each class member could establish general causation that Celexa® could have caused their specific congenital malformation. However, the Proposed Common Issue, as it was formulated, could not achieve that end. Rather than seek any linkage to a particular congenital malfunction, the question merely asked the Court to answer the general inquiry of whether Celexa® is or may be a teratogen. The plaintiffs led no evidence of a methodology to establish, on a class-wide basis, that the drug could cause any particular congenital malformation. Citing McCracken v. Canadian National Railway Company, 2012 ONCA 445, the Court found that the plaintiffs’ position “seize[d] on the superficial commonality” that citalopram is or may be a teratogen, using a “common label [to] conve[y] a false impression of commonality.’” The Court ultimately found that this class proceeding, if accepted as framed, would amount to little more than a general commission of inquiry into whether citalopram is a teratogen.

The Court went on to nonetheless consider the second aspect of the Proposed Common Issue, relating to the duty to warn, ultimately finding that this proposed question also failed, for two reasons. Firstly, and most obviously, given that the first part of the Proposed Common Issue could not succeed, the corresponding inquiry relating to the underlying duty to warn also failed, particularly in view of the fact that general causation could not be established without individual trials based on the particular congenital malformation.

Secondly, the Court held more generally that the duty to warn applies only to specific risks. Accordingly, the jurisprudence did not impose a duty to warn of general “harm” or general “teratogenicity”, which does not disclose the particular risk at issue. Citing the leading case on duty to warn— Hollis v. Dow Corning Corp., 1995 CanLII 55 (SCC) (Hollis)—the Court noted that a duty to warn can only arise with respect to specific risks and can only arise for material risks “of which [the manufacturer] has knowledge or ought to have knowledge.” With respect to reasonable foreseeability, the Court found that any particular congenital malformation would require analysis of the etiology for each such malformation. The Court in Hollis also established that, even where a duty to warn exists, the required explicitness of the warning varies with the danger. A general statement of a risk of harm or a risk of congenital malformations, such as that advanced by the plaintiffs in Price, cannot provide the court with the ability to assess the gravity or probability of the risk. As such, in the case of pharmaceutical product liability, the explicitness of the product monograph warning cannot be considered.

The Court ultimately concluded that neither of the two proposed inquiries gave rise to common issues that could be certified under section 5(1)(c) of the CPA. In the alternative, the Court denied certification on the basis that the class action was not the preferable procedure, given that individual issues would overwhelm any benefit from a common determination of teratogenicity and a concomitant duty to warn of such teratogenicity.


The analysis and conclusions reached by Justice Glustein in Price are notable for several reasons. Firstly, this decision establishes that a proposed common issue must be framed in a manner that can, if accepted, sufficiently advance the litigation. Without seeking to establish some form of general causation, a class proceeding amounts to nothing more than a commission of inquiry that fails to advance the positions of the parties in any meaningful way. Secondly, the Price decision clarifies that a duty to warn cannot give rise to a common issue if general causation cannot first be established. Finally, Justice Glustein’s findings reaffirm that an allegation of a duty to warn can only apply to specific risks – whether identified narrowly or broadly. Without disclosing the specific risk at issue, a Court cannot impose a generalized duty to warn.

This decision is critical in reminding plaintiffs of the necessity of carefully formulating their proposed common issues in a class action, thus allowing defendants to properly understand the scope of the case they must meet.