Skip to content

Our Ontario Lawyers

When success matters, there is no substitute for the advantage that comes from experience.

Search for a lawyer below:


Search Results

We're sorry, We cannot locate any lawyers with that criteria. Please search again.

Sort By:

Experience and Expertise:

How Can We Help? We’ll be happy to match you to the right qualified Lerners Lawyer.

A Little Help from Our Friends (of the Court): Public Interest Interventions in Ontario Courts

16 minute read

At the end of last year, I wrote a series of articles about public interest and environmental interventions in Federal Court proceedings: “Interventions in Federal Court: A (Nearly) New Approach”, “Intervening in the ‘Interests of Justice’ in the Federal Courts”, and “Environmental Interventions in Federal Court Proceedings”. Following that series, this article will provide a concise overview of public interest interventions in Ontario proceedings. Specifically, this article considers: the applicable rules for intervention; the various factors Ontario courts consider in determining whether to grant leave to intervene; and a few areas where interventions in the public interest are most frequent - constitutional law, class actions, and environmental litigation.

Rule 13 of the Rules of Civil Procedure

Pursuant to the Rules of Civil Procedure, RRO 1990, Reg 194, Rule 13, a court may grant leave to intervene in civil proceedings to a party in two capacities: (1) as an added party (Rule 13.01); or (2) as a friend of the court (Rule 13.02). This article focuses on Rule 13.02 interventions as they are more relevant to public interest litigation.

Rule 13.02 states:

Any person may, with leave of a judge or at the invitation of the presiding judge or master, and without becoming a party to the proceeding, intervene as a friend of the court for the purpose of rendering assistance to the court by way of argument.

Simple enough in its wording, the language of this rule is clearly discretionary. Accordingly, the jurisprudence has developed a number of considerations to help guide judges in the exercise of that discretion.

Elements of an Amicus Curiae1 Intervention

In Jones v Tsige,Watt JA described the governing principles for leave to intervene as a friend of the court as “largely uncontroversial”.

The principles governing leave to intervene have been largely uncontroversial since 1990, when Dubin CJO opined that the proper matters to be considered in determining whether to grant leave to intervene are:

(a) the nature of the case;

(b) the issues which arise; and

(c) the likelihood of the applicant being able to make a useful contribution to the resolution of the appeal without causing injustice to the immediate parties.3

Subsequently, McMurtry CJO expanded on the first criterion, and some courts have since added the explicit consideration whether the issues are essentially private in nature or whether they involve a public interest component.4 Where the case is essentially a private dispute, “the standard to be met by the proposed intervenor is more onerous or more stringently applied”.5 However, this more onerous threshold applicable to private litigation may be relaxed when public policy issues arise or matters of public interest are involved.6

It should be noted that “resolution of the appeal” in the third consideration equally applies to the resolution of the issues in non-appeal proceedings.7 In some cases, this third criterion has been expressed as two separate factors: (i) whether the applicant will make a useful contribution; and (ii) whether the applicant will cause injustice to the immediate parties.8

Regardless of how the factors are framed, the ultimate issue is whether the proposed intervenor will render “assistance to the court by way of argument.” To that end, the onus is on the applicant to demonstrate the court’s ability to determine the issues before it would be enhanced by the proposed intervention.9 The likelihood that intervention will be of assistance depends on numerous variables, including the experience and expertise of the proposed intervenor.10

Amicus curiae need not be neutral, abstract and objective to be of assistance to the court.11 As David Scriven and Paul Muldoon pointed out, the language of Rule 13.02 contemplates an intervenor rendering assistance “by way of argument”:

While the old case law implicitly assumes that a friend of the court cannot provide “assistance” when it intends to advocate its point of view, the language of Rule 13.02 appears to deny this traditional argument. The rule states that any person may intervene as a friend of the court for the purpose of rendering assistance to the court by way of argument. The term “argument” literally means to “persuade by giving reasons” and thus directly imports the notion of advocacy in such applications.12

That said, “me too” interventions have not been viewed favourably by the courts.13 In order to render assistance, proposed intervenors must be able to offer more than repetition of a party’s evidence and argument or a slightly different emphasis on arguments already made by the parties.14

This type of repetition is one type of injustice a court may cite in denying leave to intervene. Other types of injustice militating against intervention include: the late timing of the proposed intervention;15 additional evidence the proposed intervenor seeks to have added to the record;16 new arguments raised for the first time by the intervenor requiring a reply from the parties.17 However, even where injustice may result, “the likelihood of a useful contribution should exert the greater influence”.18

It should be noted that different approaches and practical considerations on motions for leave to intervene will arise depending on, for example, whether the proposed intervenor has intervened in the proceedings at lower levels or is a new intervenor on appeal, or whether multiple proposed intervenors might consider forming “blocks” on various issues arising in the proceeding. Other ever-present practical considerations in interventions and other public interest litigation will involve dealing with costs, but these are topics for consideration in another article.

With those governing principles in mind, the remainder of this article considers a few examples of proposed interventions in different contexts.

Constitutional Law

Beginning with Peel, Dubin CJO recognized that in constitutional and Charter cases the stringent rules governing interventions should be somewhat relaxed. In Authorson, McMurtry CJO explained: “This approach ensures that the court will have the benefit of various perspectives of the historical and sociological context, as well as policy and other considerations that bear on the validity of legislation.”19

However, the mere fact that litigation involved constitutional issues is not an open door to intervention. Even in constitutional and Charter cases, where the issues on which a proposed intervenor seeks leave to make arguments are not constitutional in nature, the applicant will not benefit from this relaxed standard.20 On the other side of the coin, the fact that proposed intervenors are prepared to make more sweeping constitutional arguments does not mean they will be able to add or contribute to the resolution of the legal issues between the parties.21

In two public law cases currently on their way to the Supreme Court of Canada, Groia v Law Society of Upper Canada and Trinity Western University v Law Society of Upper Canada, (TWU) intervenors have been deeply involved. In both Groia22 and TWU23, Nordheimer J cited the following passage from the Court of Appeal leave to intervene judgment in Bedford v Canada (Attorney General):24

[W]here the intervention is in a Charter case, usually at least one of three criteria is met by the intervener: it has a real substantial and identifiable interest in the subject matter of the proceedings; it has an important perspective distinct from the immediate parties; or it is a well-recognized group with a special expertise and a broadly identifiable membership base.

Justice Nordheimer confirmed the primacy of the Peel factors, stating that this passage from Bedford was simply a useful tool to determine the usefulness of a proposed intervention in Charter cases.

In TWU, Nordheimer J also pointed out that in constitutional and Charter cases, where multiple entities apply for leave to intervene making arguments on either side of the issues at bar, “the court should take into account the general desire that there should, in the end result, be some balance between the positions to be advocated when granting intervener status.”25

Class Actions

Class proceedings are another context in which public interest interventions are likely to arise. The governing principles remain the same, but as Perell J suggested in Fontaine, in addition to the court’s jurisdiction to add intervenors as parties or as friends of the court pursuant to Rule 13, the court has broad powers pursuant to section 12 of the Class Proceedings Act, 199226 to make any order it considers necessary to ensure the fair and expeditious determination of the class proceeding on such terms as the court considers appropriate.27 This would include the addition of intervenors in class action proceedings.

In addition to providing additional authority to grant leave to intervene, the Class Proceedings Act may also contain reasons for a court to deny intervention. For example, in Fairview Donut Inc. v The TDL Group Corp.,28 a group of franchisees banded together as the Concerned Franchisees Group, and sought leave to intervene in certification proceedings in order to oppose certification. Justice Lax denied leave to intervene, noting the opt-out mechanism provided in the Class Proceedings Act was the appropriate way for the proposed intervenors to express their concerns.29

Another interesting intervention case in the class action context can be found in Andrews v Ontario.30 In that case, Andrews had opted out of a certified class action and pursued private litigation against the Province. When Ontario brought a motion for summary judgment, the representative plaintiff in the class action, Mayotte,31 sought leave to intervene, ostensibly to bolster Andrews’ position and avoid the risk of an unfavourable precedent being set which would impact the chances of success for the class action. Again, leave to intervene was denied, because, among other reasons, section 13 of the Class Proceedings Act expressly provides a mechanism by which a representative plaintiff can seek a stay of any individual actions that might adversely impact a class action.32

Environmental Litigation

As concerns for the health of the environment and environmentalism increase, so too does environmental litigation. By its very nature litigation to protect or preserve the natural environment is in the public interest; thus litigation which purports to do so falls within the category of public interest litigation. Intervenors in environmental litigation might include environmental NGOs, industry groups, or even government entities like the Environmental Commissioner of Ontario.

However, despite its prima facie expertise in environmental issues and public policy concerns, even the Environmental Commissioner of Ontario has not been successful in applications to intervene in at least two major environmental cases: Pearson v Inco and Lafarge v Ontario.33 In both, the court was concerned with the way in which the Commissioner attempted to expand the record significantly, and was skeptical about whether the Commissioner’s argument would provide anything more than repetition of the parties’ submissions. In Pearson v Inco, however, Doherty JA granted leave to the Commissioner to intervene on the costs order, which was said to raise public interest concerns.34 These cases demonstrate that even an apparently well-suited candidate to be amicus curiae in environmental litigation still must satisfy the criteria for intervention.

A final comment on environmental interventions is warranted, as there is a tendency in this type of litigation for entities or coalitions to be created for the sole purpose of advancing some position in litigation or political lobbying. In Lafarge, the Industry Coalition for Environmental Fairness Inc. was created for precisely that purpose – intervening in the judicial review of an Environmental Review Tribunal decision. Justice Himel was not persuaded the ICEF had any real experience in bringing a unique perspective to the court, as it was incorporated for the sole purpose of seeking to intervene. Ultimately, ICEF did not meet its onus of showing it would render assistance to the court, beyond merely repeating the arguments of Lafarge, a member of two of ICEF’s constituent organizations.


As in Federal Court proceedings, interventions provide a unique avenue by which the courts in Ontario may be presented with broad, divergent perspectives, especially in matters of public interest. That said, as with the Federal Court rules and jurisprudence surrounding interventions, Ontario courts have not been laissez-faire in their approach to interventions. Proposed public interest intervenors would be well-advised to familiarize themselves with the jurisprudence and prudent to avoid the errors of previous failed interventions, else they waste judicial resources, the parties’ efforts, and their own time.

1Amicus curiae is the Latin term meaning “friend of the court”.

2Jones v Tsige (2011), 106 OR (3d) 721 (CA), at para 20.

3Peel (Regional Municipality) v Great Atlantic & Pacific Co. of Canada Ltd. (1990), 74 OR (2d) 164 (CA), at 167.

4Authorson (Litigation Guardian of) v Canada (Attorney General) (2001), 147 OAC 355 (CA), at paras 7-9; 1162994 Ontario Inc. v Bakker (2004), 184 OAC 157 (CA), at para 6.

5Jones v Tsige, at para 23; Fontaine v Canada (Attorney General), 2014 ONSC 3781, at para 21.

6Childs v Desormeaux (2003), 67 OR (3d) 385 (CA), at paras 3 and 10.

7Fontaine, at para 23.


9Ontario (Attorney General) v Dieleman (1993), 16 OR (3d) 32 (Gen Div); M. v H. (1994), 20 OR (3d) 70 (Gen Div).

10Jones v Tsige, at para 25.

11Childs, at para 13.

12David Scriven and Paul Muldoon, “Intervention as a Friend of the Court: Rule 13 of the Ontario Rules of Civil Procedure” (1986) 6 Advocates’ Q. 448 at 456-57, cited with approval in Childs, at para 14.

13Jones v Tsige, at para 29; Peel, at para 8.

14Stadium Corp. of Ontario Ltd. v Toronto (City) (1992), 10 OR (3d) 203 (Div Ct), at 208; Fontaine, at para 21; see also R. v Finta, [1993] 1 SCR 1138, at para 5.

15Oakwell Engineering Ltd. v EnerNorth Industries Inc., [2006] OJ No 1942 (CA), at para 13.

16Tadros v Peel Regional Police Service, 2008 ONCA 775, at paras 8 and 10; Childs, at para 18; Bakker, at para 9.

17Pearson v Inco Ltd., 2005 CanLII 5393 (ON CA), at para 6.

18Jones v Tsige, at para 28; Childs, at paras 13-14; Oakwell, at para 9.

19Authorson, at para 7; see also Dieleman.

20Ibid, at para 14.

21Stadium Corp., at 208.

22Joseph Groia v Law Society of Upper Canada, 2014 ONSC 6026, at para 4.

23Trinity Western University v Law Society of Upper Canada, 2014 ONSC 5541, at para 5.

24Bedford v Canada (Attorney General), 2009 ONCA 669, 98 OR (3d) 792, at para 2.

25TWU, at para 10.

26SO 1992, c 6.

27Fontaine, at para 24.

28Fairview Donut Inc. v The TDL Group Corp., 2008 CanLII 60983 (ON SC).

29Ibid, at paras 8 and 11.

30Andrews v Ontario, 2012 ONSC 3146.

31Mayotte v Ontario, 2010 ONSC 3765.

32Andrews, at para 16.

33Lafarge Canada Inc. v Ontario Environmental Review Tribunal, 2008 CanLII 6870 (ON SCDC).

34Pearson v Inco, at paras 7-8.

The content contained in these blogs is intended to provide information about the subject matter and is not intended as legal advice. If you would like further information or advice on any of the subjects discussed in a blog post, please contact the author.

LERNx Sidebar


LERNx is committed to making the law easier to access for all by publishing high-quality and industry-leading content.

Jacob R. W. Damstra

We are here to help.

Do you have any questions about your unique scenario? Feel free to reach out directly by visiting my Lerners Profile View My Full Profile