What is the evidentiary burden placed on plaintiffs at the certification stage of a class action?

The second criterion listed is the amount and nature of discovery, evidence or investigation. Again, this cannot properly be taken into account at the certification stage. There has been no discovery at this stage and the case law is clear that this cannot be counted against the plaintiffs. In Lambert v. Guidant, [See Note 30 below] Cullity J. discussed the reasons for the low evidentiary burden placed on plaintiffs at the certification stage, noting the inability of plaintiffs to muster all of the evidence until after production and discovery. He held, at paras. 70-71: Most fundamentally, the purpose of the certification stage of a class proceeding is to determine whether the requirements in section 5(1) of the CPA are satisfied and, if so, to define the issues to be tried. It would be a reversal of the process to permit certification to be determined by deciding issues that are likely to be front and centre at a trial. The use that defendants' counsel sought to make of evidence on this motion was not consistent with the above principles. The fact that productions and examinations for discovery do not occur prior to certification is consistent with the legislative intention that the certification stage is not the time for facts that bear on the merits of a plaintiff's claims to be determined. It [page633] would be inconsistent with the purpose of discovery -- and manifestly unfair to plaintiffs -- to deny certification on the basis of findings of fact that may be in dispute and that would likely be the subject of discoveries prior to trial. To a very large extent, this is what defendants' counsel urged me to do in this case.