Executive Summary: Key Legal and Evidentiary Issues

• Scope of a judge’s discretion under article 206 C.p.c. to refuse a modification of the class description that would introduce a “demande entièrement nouvelle” unrelated to the authorised collective action
• Significance of the authorisation judgment and the municipal regulation (Règlement 547-5-1) as the defining framework for the class, limiting additions to residents affected by the post-2018 truck route changes
• Insufficiency of evidence linking the chemin de la Butte-aux-Renards (CBR) residents’ alleged prejudice to the specific regulatory change underlying the authorised class action
• Impact of prior related litigation by CBR residents (Benoit c. Groupe CRH Canada inc.) and the advanced procedural stage of the class action on delay, proportionality, and the interests of justice
• Interpretation of article 31 al. 2 C.p.c. on leave to appeal interlocutory judgments, including the absence of irreparable prejudice where the proposed added residents are not yet parties and may still bring separate proceedings
• Limited weight of the risk of multiple proceedings and potentially inconsistent judgments when weighed against proportionality and the low prospects of success on appeal

Background and facts of the dispute

The underlying matter arises from a class action (action collective) initiated by Jessy Riendeau against the Ville de Varennes. As representative plaintiff, Riendeau alleges that a municipal regulation changing the heavy-truck circulation pattern has caused abnormal neighbourhood disturbances and related harms to certain residents of the municipality. The regulation at the centre of the authorised class action is Règlement 547-5-1, which amended the existing truck-traffic regulation to modify the list of prohibited roads and the circulation plan. This amendment, which took effect on 16 July 2018, allowed heavy trucks to circulate on streets that were previously off-limits. The authorised class is defined by reference to residents living on certain streets of Varennes since 16 July 2018, with common questions expressly tied to the impacts of the new truck route created by Règlement 547-5-1 and its alleged consequences on noise, vibrations, dust, enjoyment of property, environmental quality, and property values.

The earlier authorisation judgment and policy framework

In March 2020, the Superior Court rendered the authorisation judgment in Dulude c. Ville de Varennes, which both authorised the class action and structured its legal and factual framework. The class was defined by residence on designated streets since 16 July 2018, and the core common questions all revolved around the adoption and effects of Règlement 547-5-1. These questions include whether members suffer abnormal neighbourhood inconveniences due to the new heavy-truck route, whether the City incurred faultless or civil liability by adopting the regulation, and whether members can obtain injunctive relief, compensatory and moral damages, and sums linked to loss of property value. The Court of Appeal emphasises that, taken together, the class description and common questions make the regulation’s coming into force the “cadre de référence” of the case, and that the regulation did not concern the chemin de la Butte-aux-Renards, which had not been subject to a prohibition under earlier truck-traffic regulations. In practical terms, the “policy terms” at issue are municipal regulatory provisions governing where heavy trucks may circulate, rather than insurance or contractual clauses. The clauses at issue are those that altered the circulation prohibitions and plan, thereby permitting heavy trucks on streets previously protected; this regulatory change is what allegedly generated the harm suffered by the authorised class.

The motion to modify the group and change the representative

Several years into the litigation, Riendeau sought to modify the description of the group under article 206 C.p.c. to add all persons residing or having resided, or owning or having owned agricultural operations, since 16 July 2018 on the chemin de la Butte-aux-Renards (CBR). She also requested that, if this expansion were granted, she be replaced as representative plaintiff by a CBR resident. The Superior Court (Finn J.) rejected the motion. The judge reasoned that the requested modification would not simply enlarge an existing group but would instead graft onto the authorised action a new set of claims arising from different facts and a different causal chain. While the existing class is anchored in the 2018 truck-route change brought about by Règlement 547-5-1, the CBR residents’ complaints predated that regulation and related largely to long-standing traffic generated by nearby quarries and industrial installations. Critically, the plaintiff did not provide any concrete evidence that the 2018 regulation changed truck traffic on the CBR, or that the new truck route had any real effect on that road. The trial judge concluded that adding CBR residents, many of whom had experienced truck-related inconvenience before 2018, would create an entirely new claim disconnected from the originally authorised cause of action and common questions.

Evidence concerning CBR residents and prior litigation

The Court of Appeal recounts that CBR residents allege they have suffered serious abnormal neighbourhood disturbances, including noise and heavy truck traffic, at least since 2014. Their alleged prejudice is tied to the operations of Carrière Demix (Groupe CRH Canada inc.) and Bau-Val in Varennes, and to KPH installations in Montréal in connection with the Turcot project. Those residents pursued their own distinct action in damages, injunction, and declaratory relief against these companies and the Ville de Varennes for the 2014–2021 period. That action resulted in partial success only against Groupe CRH Canada inc., for truck-traffic impacts during 2016 and 2017, and the Ville was expressly found not liable for the inconveniences experienced by CBR residents due to truck traffic to and from CRH and Bau-Val installations. The Superior Court’s conclusions in that separate case were upheld on appeal, and the Supreme Court of Canada refused leave to appeal. Against this background, the Court of Appeal in Riendeau notes both the existence of prior, final litigation involving CBR residents and the already complex and protracted procedural history of the present class action, which has involved multiple trips to the Court of Appeal and numerous case-management hearings and suspensions in the Superior Court over more than seven years.

The Superior Court’s application of article 206 C.p.c.

Under article 206 C.p.c., a judge may allow modification of the class description, provided that three cumulative conditions are met: the modification does not delay the progress of the proceedings, is not contrary to the interests of justice, and does not result in a completely new claim unrelated to the initial demand. Although the case law recognises that the right to modify the class description should be interpreted liberally and that refusals are exceptional, the trial judge retains a broad discretion to assess these criteria in the context of the authorised action. In applying these principles, Finn J. examined the original authorisation judgment and the structure of the action, including the linkage between the class definition and the regulatory change in 2018. He concluded that the CBR residents’ alleged harm derived from a different factual basis (long-standing quarry and industrial truck traffic), that there was no evidence of a specific impact of Règlement 547-5-1 on the CBR, and that the proposed change would therefore amount to an entirely new and disproportionate claim. He also considered the stage of the proceedings, the absence of a satisfactory explanation for the late request, and the likelihood that adding about 50 new members with a distinct factual matrix would significantly delay the case, especially in relation to the protocol of the instance, examinations, undertakings, and expert evidence. On these grounds, he refused to modify the group and, as a consequence, did not substitute the representative plaintiff.

The application for leave to appeal and the Court of Appeal’s analysis

Riendeau then sought leave from the Court of Appeal to challenge the interlocutory judgment under article 31 al. 2 and article 357 C.p.c. She argued that the trial judge erred in law by interpreting the authorisation judgment instead of simply applying article 206 C.p.c., that he unduly restricted the group definition, and that his decision infringed the guiding principles of civil procedure, including access to justice and proportionality. She also maintained that the judgment effectively decided part of the dispute by closing the door on CBR residents, caused irreparable harm by preventing them from accessing collective redress, and risked multiple individual and collective proceedings with potentially conflicting outcomes. The Court of Appeal, sitting through a single judge (Lachance J.A.), applied the established test for leave to appeal an interlocutory decision. To obtain leave, the applicant had to show that the judgment either decides part of the dispute or causes irreparable prejudice within the instance and, in addition, that the proposed appeal raises a question that warrants the Court’s attention and has reasonable prospects of success, all while respecting proportionality and the best interests of justice.

No error of principle and proper reliance on the authorisation framework

The Court of Appeal rejected the contention that the trial judge improperly “interpreted” the authorisation judgment. It held that, to assess whether a proposed modification introduces a new, unrelated claim or undermines proportionality, a judge must necessarily refer back to the structure and scope of the authorised action. Here, the authorisation judgment and subsequent modifications clearly tied the class and common issues to the effects of Règlement 547-5-1 and its 2018 effective date. The Court considered it both legitimate and necessary for the judge to situate the requested modification within this framework. Moreover, on the evidentiary record, the trial judge was entitled to find that the applicant had produced no proof that the regulatory change affected the CBR, and that the CBR residents’ alleged harm arose from a distinct factual context that pre-dated and did not depend on the 2018 regulation. On that basis, the conclusion that adding CBR residents would create an entirely new demand and would be disproportionate was not tainted by error of principle or an unreasonable exercise of discretion.

Proportionality, delay, and irreparable prejudice

The Court also addressed the applicant’s criticism that the judge over-emphasised delay and the late timing of the request. While tardiness alone rarely justifies refusal of a class modification, it remains a relevant consideration, particularly in a complex case that has already generated significant procedural activity and multiple appellate steps. Given the age of the file, the existing suspensions, and the procedural work still required, it was open to the judge to find that adding approximately 50 new members with a separate factual history would materially slow the proceedings and undermine the objectives of timely and efficient civil justice. As to irreparable prejudice, the Court underlined that the dispositive part of the judgment—not its reasons—must be examined. The decision did not rule on the merits of the class action or finally determine the rights of the existing class members; it simply refused to enlarge the group to include non-parties. Those CBR residents remain free to bring their own actions, individually or collectively, notwithstanding the prior partial litigation in Benoit. Consequently, no irreparable prejudice within the meaning of article 31 al. 2 C.p.c. was established. The theoretical risk of multiple proceedings and inconsistent judgments, while not insignificant, did not suffice to tip the balance toward granting leave, particularly where the proposed appeal had no reasonable chance of success.

Outcome and financial consequences

In the result, the Court of Appeal held that the applicant failed to demonstrate any error of principle or unreasonable exercise of discretion in the trial judge’s application of article 206 C.p.c. It further concluded that the challenged interlocutory judgment neither decided part of the underlying merits nor caused irreparable prejudice to a party in the instance, and that the proposed appeal did not raise a question deserving the Court’s attention or presenting reasonable prospects of success. For these reasons, Justice Lachance, J.A. dismissed the application for leave to appeal and ordered that it be rejected with costs. The successful party in this appellate stage is therefore the Ville de Varennes, which successfully resisted the application for leave. The judgment simply awards “frais de justice” (costs) in its favour and does not fix any specific monetary amount for costs, nor does it grant or quantify any damages; accordingly, the total monetary award in favour of the City cannot be determined from this decision.