Canada’s Antitrust Litigation Framework

Canada was a pioneer in competition law, becoming the first country in the world to enact modern antitrust legislation with the Anti-Combines Act, 1889, which was designed to address anti-competitive agreements and monopolistic practices. Over the following century, Canada’s competition regime evolved through a series of legislative reforms, including the Combines Investigation Act, before being fundamentally modernised through the enactment of the Competition Act in 1986.

Canada’s modern antitrust litigation framework is primarily governed by the Competition Act. With the exception of collective bargaining agreements (Section 4), underwriters of securities (Section 5), and amateur sports (Section 6), the Competition Act applies to all business and government activities in Canada. The Act includes civil and criminal offences and prohibits anti-competitive conduct, including cartel agreements, bid-rigging, abuse of dominance, anti-competitive collaborations, and deceptive marketing practices. It also establishes the remedies available for violations, including damages, injunctions, and administrative monetary penalties.

Competition matters are often heard by the Competition Tribunal, a specialised adjudicative body established under the Competition Tribunal Act. The Tribunal has jurisdiction over various civil reviewable practices under the Competition Act, including abuse of dominance, anti-competitive agreements, refusal to deal, and certain deceptive marketing practices.

The Competition Bureau, led by the Commissioner of Competition, is Canada’s federal competition law enforcement agency. Among other legislation, the Bureau is responsible for administering and enforcing the Competition Act. The Bureau investigates potential violations and may bring proceedings before the Competition Tribunal or the courts.

Private antitrust class actions are heard by provincial superior courts or the Federal Court. Antitrust class actions are governed by the applicable provincial class proceedings legislation or the Federal Court Rules and are commonly used to pursue damages arising from alleged cartel conduct, such as price-fixing and bid-rigging.

Overview of the Most Important or Novel Antitrust Cases in Canada

Please see 1.2 Recent Developments.

Expansion of Private Access to the Competition Tribunal

Recent legislative amendments and case law have significantly expanded the role of private enforcement in Canadian antitrust law.

The most important legislative development is the expansion of private access to the Competition Tribunal. Historically, private parties had limited ability to bring proceedings before the Tribunal. Amendments in 2025 broadened the categories of conduct for which private applications may be brought, including anti-competitive agreements and deceptive marketing practices. They also introduced a new “public interest” basis for obtaining leave and empowered the Tribunal to award monetary relief in certain cases, including amounts based on the benefits derived from the impugned conduct.

Martin v Alphabet Inc.: Defining the New Public Interest Standing Test

The Competition Tribunal’s first decision on the public interest standing test was released in Martin v Alphabet Inc. The Tribunal established a three-part test for granting leave, requiring an applicant to demonstrate: (i) a substantial and genuine competition law issue; (ii) a genuine interest in the matter; and (iii) that the proceeding is a reasonable and effective means of bringing the issue before the Tribunal. The Tribunal emphasised that public-interest standing should be available where competition issues warrant adjudication, even if the applicant cannot demonstrate that it was directly affected by the impugned conduct. As the first decision interpreting the amended leave provisions, Martin is expected to play a significant role in shaping the future development of private antitrust litigation in Canada.

Private enforcement of Canadian competition law may occur through three distinct mechanisms. Private parties may seek to trigger public enforcement by (i) filing complaints with the Competition Bureau, (ii) pursuing damages through court proceedings under Section 36(1) of the Competition Act, or (iii) seeking remedies directly before the Competition Tribunal through the private access regime established under Section 103.1.

Complaints to the Competition Bureau

The first avenue for private enforcement is through complaints to the Competition Bureau. Although complainants cannot obtain damages directly through this process, they may prompt the Commissioner of Competition to investigate potentially anti-competitive conduct.

The Act provides both informal and formal complaint mechanisms. An informal complaint may be submitted by a single resident and gives the Commissioner discretion to decide whether any action should be taken. The Commissioner is not required to investigate, provide reasons, or report the outcome to the complainant.

A more structured process exists where six residents jointly request a formal inquiry. Such a request may lead to an inquiry under Section 10 of the Competition Act where the Commissioner has reason to believe that a civil remedy may be available, that a criminal provision of the Act has been breached, or that an order of the Competition Tribunal or a court has not been respected. However, the Commissioner retains broad discretion and is not obliged to commence an inquiry merely because a request has been filed. Formal requests require a response. If the Commissioner refuses to commence an inquiry, the Commissioner must report the reasons for refusal to the Minister, who may request further inquiries but cannot compel the Commissioner to proceed.

Private Damages Actions Under Section 36(1)

Section 36(1) of the Competition Act provides a statutory cause of action that allows individuals and businesses to seek compensation for loss or damage arising from certain violations of the Act. In particular, the provision applies to breaches of the criminal provisions contained in Part VI, including price-fixing and bid rigging conspiracies and certain deceptive marketing practices.

Canadian courts have interpreted the concepts of “loss” and “damage” broadly, thereby extending the availability of private actions beyond those who dealt directly with the alleged wrongdoer. In the Supreme Court of Canada’s 2013 trilogy of decisions, Pro-Sys Consultants Ltd v Microsoft Corporation, Sun-Rype Products Ltd v Archer Daniels Midland Company, and Infineon Technologies v Option Consommateurs, the Court confirmed that indirect purchasers may advance claims under Section 36. These are consumers or businesses that purchased products through intermediaries but allegedly bore the effects of an unlawful overcharge passed down the supply chain.

The courts have also recognised claims by so-called umbrella purchasers, namely purchasers who bought from firms that were not members of the alleged cartel but who claim that the cartel’s conduct inflated prices across the broader market.

Private Applications to the Competition Tribunal Under Section 103.1

A third avenue is the private application regime before the Competition Tribunal under Section 103.1. Recent amendments have expanded access to the Tribunal. With the notable exception of mergers, private parties may now seek leave to pursue most civil reviewable practices.

The Tribunal may refuse leave where the matter is already under investigation by the Commissioner, where the Commissioner has settled the matter and discontinued a related inquiry, where the matter has already been the subject of an application by the Commissioner, or where the conduct is protected by an environmental collaboration certificate issued under the Competition Act.

A party seeking leave must serve the Commissioner of Competition with a certified copy of its application. Within 48 hours of service, the Commissioner must certify to the Tribunal whether the matter is already the subject of an inquiry by the Competition Bureau or whether a previous inquiry was discontinued as a result of a settlement. In rare cases, the Commissioner may commence an inquiry during that 48-hour period, in which case the certification may prevent the Tribunal from considering the private leave application.

Leave requirements vary according to the provision invoked. For abuse of dominance, refusal to deal, exclusive dealing, tied selling and market restriction cases, the applicant must demonstrate that the impugned conduct directly and substantially affected its business, or that granting leave would be in the public interest. For price maintenance, direct impact on the applicant’s business is sufficient. For deceptive marketing practices, leave may be granted where the Tribunal is satisfied that the application is in the public interest.

The Commissioner may intervene at any stage of the proceeding and provide submissions regarding the issues raised by the application, including whether the Commissioner supports or opposes the granting of leave. Further, the Commissioner’s involvement may continue after a private access proceeding has been resolved. Where the parties enter into an agreement that disposes of the application, including a consent agreement registered with the Tribunal, copies of the agreement must be served on the Commissioner. The Commissioner may apply to the Tribunal to vary or rescind an agreement resolving a private access application. These mechanisms reflect the continuing supervisory role of the Commissioner and are intended to ensure that private enforcement complements, rather than conflicts with, the public enforcement of the Competition Act.

Jurisdiction Over Antitrust Proceedings

Canada’s antitrust cases are allocated among several courts and adjudicative bodies depending on the nature of the proceeding.

• Private damages actions and competition class proceedings proceed before provincial superior courts or the Federal Court.
• Criminal matters under the Competition Act, including cartel conduct and bid-rigging offences, may be heard by provincial superior courts or the Federal Court, depending on the proceeding.
• Most civil reviewable matters, including mergers, abuse of dominance and competitor collaborations, are heard by the Competition Tribunal, a specialised adjudicative body with expertise in competition law and economics. Appeals from the Competition Tribunal are heard by the Federal Court of Appeal.

The Federal Court has jurisdiction over applications for judicial review of certain competition-related decisions.

Competition Tribunal orders are enforceable through contempt proceedings in court. In Chrysler Canada Ltd. v Competition Tribunal, the Supreme Court confirmed the Tribunal’s authority to sanction non-compliance with its orders.

In Canada, the National Competition Authorities are comprised of (i) the Competition Bureau and (ii) the Competition Tribunal.

The Competition Bureau and Antitrust Proceedings

The Competition Bureau is the independent federal agency responsible for administering and enforcing the Competition Act, as well as several consumer protection statutes. It investigates anti-competitive conduct, including cartels, abuse of dominance, mergers, deceptive marketing practices and bid-rigging, and may bring civil proceedings before the Competition Tribunal or refer criminal matters to the Attorney General of Canada.

While the Bureau plays a central enforcement role, it is not a court and its decisions, policies and enforcement guidelines are not binding on civil courts, although they often carry significant persuasive weight. The Bureau may also participate directly in proceedings before the Competition Tribunal and, in some cases, court proceedings.

Binding Effect of Competition Tribunal Decisions

The Competition Tribunal is a specialised adjudicative body that hears most civil competition matters. Its decisions are binding on the parties unless overturned on appeal by the Federal Court of Appeal.

In Canada (Director of Investigation and Research) v Southam Inc., the Supreme Court held that appellate courts should show considerable deference to the Tribunal’s economic assessments, including market definition. However, the continued application of Southam’s standard of review has been questioned following the Supreme Court’s decision in Canada (Minister of Citizenship and Immigration) v Vavilov, which reformulated the framework for judicial review. Whether Southam remains fully applicable in appeals from the Competition Tribunal has not been settled.

The Impact of Foreign Competition Decisions on Canadian Court Proceedings

Decisions of foreign competition authorities are not binding on Canadian courts but they can be persuasive. Canadian courts may consider foreign findings and settlements as part of the factual record, particularly in follow-on cartel class actions. Canadian courts nevertheless conduct their own independent assessment under the Competition Act.

Burden and Standard of Proof

The allocation of the burden of proof depends on the nature of the proceeding. In civil matters before the Competition Tribunal, including merger review and abuse of dominance cases, the Commissioner of Competition bears the burden of establishing the elements of the claim on a balance of probabilities. The same civil standard applies to private actions before Canadian courts. By contrast, criminal offences under the Competition Act, such as cartel conduct and bid-rigging, must be proven by the prosecution beyond all reasonable doubt.

Statutory Presumptions

Section 92(3) of the Competition Act creates a rebuttable presumption that a merger is likely to prevent or lessen competition substantially where specified concentration thresholds are met. Concentration is measured using the Herfindahl-Hirschman Index (HHI), calculated by summing the squares of market shares in the relevant market.

The presumption applies where:

• the HHI increases (or is likely to increase) by more than 100 points; and
• either:
1. the post-merger HHI exceeds 1,800; or
2. the parties’ combined market share exceeds 30%.

Where these thresholds are satisfied, the burden shifts to the merging parties to rebut the presumption with evidence demonstrating that the transaction is not likely to result in a substantial prevention or lessening of competition.

Probative Value of NCA Decisions

Please see 2.3 Impact of Competition Authorities.

The “Pass-on Defence” Does Not Exist in Canadian Law

Canadian law does not recognise a pass-on defence in antitrust court actions. A defendant cannot avoid liability by arguing that a claimant passed all or part of an alleged overcharge on to its own customers and therefore suffered no loss. The Supreme Court of Canada rejected the pass-on defence principally because of the evidentiary difficulties associated with tracing overcharges through complex distribution chains.

At the same time, the Supreme Court has recognised that both direct and indirect purchasers may seek damages under Section 36 of the Competition Act. In the 2013 trilogy of Pro-Sys Consultants Ltd. v Microsoft Corporation, Sun-Rype Products Ltd. v Archer Daniels Midland Company and Infineon Technologies AG v Option consommateurs, the Court confirmed that indirect purchasers who ultimately bear an overcharge may have standing to claim damages.

Accordingly, there is generally no burden on a claimant to disprove pass-on as a defence. Rather, the plaintiff must establish, on a balance of probabilities, that it suffered loss or damage caused by the alleged contravention. Where an indirect purchaser brings a claim, it bears the burden of proving that the overcharge was passed through the distribution chain and resulted in compensable harm.

Antitrust Limitation Periods

Limitation periods under the Competition Act vary depending on the type of proceeding.

For private damages actions under Section 36, a claimant must generally commence an action within two years of the impugned conduct becoming reasonably discoverable to the claimants or, if later, within two years of the final disposition of any related criminal proceedings. In Pioneer Corp. v Godfrey, the Supreme Court of Canada confirmed that this limitation period is subject to the discoverability principle, meaning that time does not begin to run until the material facts giving rise to the claim are discovered, or ought reasonably to have been discovered. In addition, the Ontario Court of Appeal in M.M. Mura Holdings Inc. v Archer Daniels Midland Company confirmed that the limitation period is postponed until the conclusion of any related criminal prosecution.

For merger review proceedings under Section 92, the Commissioner may challenge a completed merger within one year where the transaction was subject to mandatory notification or an advance ruling certificate request, and within three years for non-notifiable mergers.

Other civil reviewable matters are subject to their own statutory limitation periods. For example, applications relating to anti-competitive agreements under Section 90.1 must generally be brought within three years after the agreement has terminated, while abuse of dominance applications must be commenced within three years after the impugned conduct has ceased.

Impact of Competition Bureau Decisions on Limitation Periods

Competition Bureau investigations and civil enforcement proceedings do not generally suspend or extend limitation periods. However, where conduct results in criminal proceedings referred to the Attorney General, Section 36 expressly postpones the commencement of the civil limitation period until the underlying criminal proceedings have been finally disposed of. In practice, Competition Bureau investigations, settlements and published enforcement decisions may also assist private plaintiffs in discovering the material facts underlying a claim, which may affect the application of the discoverability principle established in Pioneer Corp. v Godfrey.

Timing and Pace of Private Antitrust Litigation

Private antitrust litigation in Canada can be lengthy, particularly where claims are pursued through class proceedings. There is no single average duration, as timelines vary depending on the forum, the complexity of the issues, and whether appeals are brought. Proceedings before the Competition Tribunal are often resolved within approximately 18 to 24 months, although complex merger and abuse of dominance cases may take considerably longer. By contrast, private competition class actions frequently span five to ten years or more. Certification (and related appeals) can take several years, and cases typically settle before reaching trial.

Statutory Basis for Class and Collective Actions

Canada has a well-established statutory framework for class proceedings. Each province has enacted class proceedings legislation, while class actions brought in the Federal Court are governed by Part 5.1 of the Federal Courts Rules. While procedural requirements vary by jurisdiction, the statutory frameworks across Canada are broadly similar and provide a structured mechanism for advancing representative claims on behalf of large groups of affected persons.

In the antitrust law context, Section 36 of the Competition Act provides a statutory cause of action for any person who has suffered loss or damage as a result of conduct contrary to the criminal provisions in Part VI of the Act, including conspiracy (Section 45), foreign directives (Section 46), bid-rigging (Section 47) and deceptive marketing (Section 52). This provision forms the basis for most competition class actions in Canada.

Recent amendments that came into force in June 2025 also introduced a new form of collective redress before the Competition Tribunal. Private parties may, with leave, seek remedies for certain civil reviewable practices, including refusal to deal (Section 75), price maintenance (Section 76), exclusive dealing, tied selling and market restriction (Section 77), abuse of dominance (Sections 78-79), anti-competitive agreements (Section 90.1) and deceptive marketing practices (Section 74.1). The Tribunal may order a disgorgement remedy to be distributed among all persons affected by the conduct, creating a collective recovery mechanism that bears similarities to a class action.

Opt-Out Regime in Canadian Class Proceedings

Canadian class proceedings generally operate on an opt-out basis. Once a class action is certified and the class definition is approved, individuals who fall within that definition are automatically included in the proceeding unless they take steps to withdraw during the court-ordered opt-out period. Class members who do not opt out are bound by any judgment or settlement reached in the action.

Following certification, courts direct how notice will be provided to class members, often through electronic publications, law firm websites, social media and newspapers.

Some provinces depart from the general opt-out model for certain non-resident class members. In particular, New Brunswick and Newfoundland and Labrador may require non-residents to opt in before participating in a class proceeding.

Direct and Indirect Purchaser Claims

Under Canadian antitrust law, both direct and indirect purchasers may seek damages under Section 36 of the Competition Act. The Supreme Court of Canada resolved a long-standing debate in its 2013 trilogy of decisions, Pro-Sys Consultants Ltd v Microsoft Corporation, Sun-Rype Products Ltd v Archer Daniels Midland Company, and Infineon Technologies AG v Option consommateurs. In those cases, the Court confirmed that Section 36 is not limited to purchasers that acquired a product directly from the alleged wrongdoer. Indirect purchasers, namely persons who purchased through one or more intermediaries in the distribution chain, may also claim losses resulting from the alleged anti-competitive conduct.

In Pioneer Corp. v Godfrey, the Supreme Court recognised claims by umbrella purchasers, being purchasers of products or services that were not sold by the alleged conspirators, but whose prices were allegedly inflated under the “umbrella” created by the anti-competitive conduct.

As a result, Canadian antitrust law generally permits claims by direct purchasers, indirect purchasers and umbrella purchasers, provided the claimant can demonstrate compensable loss or damage resulting from the impugned conduct.

Certification of Antitrust Class Actions

Antitrust class actions must be certified (or authorised in Quebec) before they proceed as class proceedings. After commencing the action, the plaintiff brings a motion seeking an order certifying the proposed class.

Subject to some nuances, in the common law provinces, the plaintiff must generally establish that: (i) the pleadings disclose a cause of action; (ii) there is an identifiable class of two or more persons; (iii) the claims raise common issues; (iv) a class proceeding is the preferable procedure; and (v) there is an appropriate representative plaintiff with a workable litigation plan.

Certification is often the most heavily contested stage of an antitrust class action. The standard of proof is low. For the first requirement, the court needs to be satisfied that it is not “plain and obvious” that the pleadings fail to disclose a cause of action, even assuming the facts pleaded are true. For the remaining criteria, a plaintiff needs to meet a slightly higher standard and show that there is “some basis in fact” that the requirement is fulfilled. Both standards are lower than the balance of probabilities standard that would be applied at trial to determine liability and assess damages.

Rules on Jurisdiction

Canadian courts determine adjudicative jurisdiction principally through the framework established by the Supreme Court of Canada in Club Resorts Ltd. v Van Breda. Under Van Breda, a court may assume jurisdiction where there is a “real and substantial connection” between the dispute and the forum. The Court identified several presumptive connecting factors, including whether the defendant is domiciled or carries on business in the province, whether the tort was committed in the province, or whether a contract connected with the dispute was made there. These factors reflect jurisdiction legislation in place in numerous provinces across Canada.

In competition cases, however, applying these principles is not always straightforward. Alleged anti-competitive conduct frequently occurs across multiple jurisdictions and may involve foreign defendants, foreign misconduct, nationwide classes, and transactions affecting purchasers throughout Canada. Defendants often challenge jurisdiction on the basis that the relevant conduct, decisions, or transactions took place outside the forum.

Rules on Applicable Law

Please see 4.4 Class Certification.

Disclosure of Documents

Documentary disclosure in Canadian antitrust litigation is governed primarily by the civil procedure rules of the court in which the action is brought. Disclosure generally follows the ordinary discovery process applicable to civil litigation.

For example, in Ontario each party is required to serve an affidavit of documents identifying all relevant documents within its possession, control or power, as well as documents for which privilege is claimed. Relevant, non-privileged documents must then be produced to the opposing parties for inspection. The scope of production is broad and may include internal communications, pricing records, market analyses, communications with competitors, and documents relating to alleged anti-competitive conduct or damages.

In antitrust class actions, discovery typically takes place following certification and is often subject to detailed case-management orders governing electronic discovery, production schedules, custodians, and search protocols.

Examinations for Discovery

After documentary production, parties may conduct examinations for discovery of opposing parties. Corporate litigants must put forward a representative to answer questions under oath regarding matters relevant to the action, including the documents produced during discovery.

Competition Bureau Materials and Privilege

Documents gathered by the Competition Bureau during an investigation are not automatically available to private litigants. Access may require a court order and may be limited by statutory confidentiality protections and public interest considerations. In addition, parties may withhold documents protected by solicitor-client privilege, litigation privilege, or other recognised forms of privilege, provided that the claim is properly asserted and disclosed in the affidavit of documents.

Legal Advice Privilege

Legal advice privilege (often referred to as solicitor-client privilege) protects confidential communications between a client and lawyer made for the purpose of seeking or providing legal advice. The protection applies to both external and in-house counsel, provided the communication relates to the provision of legal advice rather than a purely business function. The Supreme Court of Canada has repeatedly described solicitor-client privilege as a fundamental principle of justice that enjoys near-absolute protection. Privileged communications are generally immune from disclosure and may only be waived by the client.

Litigation Privilege

Litigation privilege protects documents and communications created for the dominant purpose of existing or reasonably contemplated litigation. The privilege extends beyond lawyer-client communications and may cover expert materials, witness interviews, internal investigations, and other documents prepared in anticipation of litigation. Unlike legal advice privilege, litigation privilege is not a permanent class privilege and is generally tied to the litigation for which the documents were created.

Privilege Over Documents Submitted to the Competition Bureau

The disclosure of information to the Competition Bureau does not, in itself, waive legal professional privilege. Communications subject to solicitor-client privilege remain protected even where a party is responding to a Bureau investigation.

In addition, the Bureau cannot generally compel the production of privileged communications. Section 11 production orders issued under the Competition Act do not override solicitor-client privilege, and parties routinely assert privilege when responding to investigative demands.

Separate statutory protections also apply to information obtained by the Bureau. Section 29 of the Competition Act imposes strict confidentiality obligations on information obtained through compulsory processes, merger notifications, and voluntary submissions, subject to limited exceptions. As a result, materials provided to the Bureau are not automatically available to private litigants in follow-on antitrust actions.

Nevertheless, confidentiality under Section 29 is not absolute. In appropriate circumstances, disclosure may be ordered where required by law or by a court, subject to confidentiality protections and privilege claims. Accordingly, while Bureau records may sometimes become relevant in subsequent civil proceedings, solicitor-client privilege and litigation privilege remain fully available to protect privileged materials.

Leniency Agreement and Consent Orders

Leniency agreements and consent orders are not subject to a single disclosure rule in Canada. As a general matter, registered consent agreements are public, whereas information provided to the Competition Bureau in the course of immunity or leniency applications is typically protected by statutory confidentiality provisions.

Consent Agreements Before the Competition Tribunal

Consent agreements entered into between the Commissioner of Competition and a party under Section 105 of the Competition Act are generally not confidential. Section 105 permits the parties to file a consent agreement with the Competition Tribunal for registration, after which it has the same force and effect as an order of the Tribunal. Once registered, the agreement ordinarily becomes part of the public record and is available to third parties.

That said, commercially sensitive information may in appropriate circumstances be protected through confidentiality orders or redactions, consistent with the Tribunal’s general powers to protect confidential information. The underlying evidentiary record and settlement negotiations are not necessarily public merely because a consent agreement has been registered.

Leniency and Immunity Agreements

By contrast, leniency and immunity agreements are generally afforded a high degree of confidentiality. The Competition Bureau’s immunity and leniency programmes expressly contemplate confidentiality protections for applicants, reflecting the importance of encouraging self-reporting of cartel conduct and other criminal offences under the Competition Act.

In addition, Section 29 of the Competition Act prohibits the communication of information obtained by the Bureau in the administration or enforcement of the Act, subject to limited exceptions. This protection extends to information provided voluntarily as well as information obtained through compulsory investigative processes.

Disclosure in Private Antitrust Litigation

Although leniency and immunity materials are not automatically available to private plaintiffs, confidentiality is not absolute. Canadian courts have recognised that Bureau materials may be producible where required by law or court order, subject to Section 29 confidentiality protections, public interest considerations, and applicable claims of solicitor-client privilege or litigation privilege. Accordingly, the existence of a leniency or immunity agreement may become known in follow-on civil litigation, but the underlying communications, witness statements, and investigative materials will often remain protected from disclosure.

Provincial Superior Courts

In provincial superior courts, the procedure for hearing witnesses is governed by the applicable rules of civil procedure. For example, in Ontario, examinations for discovery are governed by Rule 31 of the Rules of Civil Procedure, while evidence at trial, including the examination, cross-examination and re-examination of witnesses, is addressed through various procedural and evidentiary rules. Witness attendance may be compelled through a summons to witness under Rule 53.04. In criminal antitrust proceedings, witness testimony is governed by the Criminal Code and the applicable criminal procedure rules.

Federal Court

In the Federal Court, witness evidence is governed by the Federal Courts Rules. Examinations for discovery are addressed in Rules 234-248, while subpoenas requiring a witness to attend and testify or produce documents are governed by Rules 269-273. Witnesses may provide viva voce evidence at trial and are subject to cross-examination, while expert witnesses must comply with the additional requirements applicable to expert evidence, including the obligation to complete a prescribed certificate acknowledging that the expert has read and agrees to be bound by the Code of Conduct for Expert Witnesses.

Competition Tribunal

The Tribunal’s procedures are more flexible. Rule 2 of the Competition Tribunal Rules permits the Tribunal to “dispense with, vary or supplement” the rules to ensure matters are dealt with informally, expeditiously, and fairly. Rule 7 authorises the Registrar to issue subpoenas compelling witness attendance and the production of documents. In practice, witnesses and experts are frequently examined and cross-examined at oral hearings, but the Tribunal retains broad discretion to determine the manner in which evidence will be presented.

Expert evidence plays a central role in Canadian antitrust litigation. Courts and the Competition Tribunal frequently rely on economists, accountants, industry specialists and other experts to address issues such as market definition, market power, competitive effects, damages, pass-on, overcharge methodologies and class-wide harm. Expert opinion evidence is admissible where it satisfies the requirements established by the Supreme Court of Canada in R v Mohan and subsequent jurisprudence, including the expert’s duty to provide independent and impartial assistance to the adjudicator.

Provincial Superior Courts

In provincial superior courts, the procedure for expert witnesses is governed by the applicable rules of civil procedure. In Ontario, parties intending to call an expert witness must serve an expert report complying with Rule 53.03 of the Rules of Civil Procedure. The report must set out, among other things, the expert’s qualifications, instructions received, assumptions made, opinions expressed and the reasons supporting those opinions. Experts may be examined and cross-examined at trial in the same manner as other witnesses, although courts exercise an important gatekeeping function to determine the admissibility and scope of expert evidence. In criminal antitrust proceedings, expert testimony is governed by the Criminal Code, the applicable criminal procedure rules and the common law principles governing expert evidence.

Federal Court

In the Federal Court, expert evidence is governed by Rules 279 to 282.1 of the Federal Courts Rules. Parties must generally serve expert reports in advance of trial and may conduct examinations of expert witnesses in accordance with the Rules. Experts who testify at trial are subject to cross-examination, and the Court may appoint an independent expert or require experts to confer and identify areas of agreement and disagreement. Competition-related proceedings commonly involve extensive economic expert evidence.

Competition Tribunal

The Competition Tribunal regularly relies on expert economic and industry evidence, particularly in merger, abuse of dominance and competitor collaboration cases. Consistent with the Tribunal’s flexible procedures, Rule 2 of the Competition Tribunal Rules allows the Tribunal to dispense with, vary or supplement its Rules in order to deal with matters “as informally and expeditiously as the circumstances and considerations of fairness permit”. Expert witnesses are typically required to file written expert reports in advance of the hearing and may be examined and cross-examined at the hearing. The Tribunal also possesses broad case management powers to establish procedures governing expert evidence, including the timing of reports, reply reports, witness statements and the conduct of expert testimony. Given the highly economic nature of many antitrust disputes, expert evidence is often among the most significant evidence before the Tribunal.

Assessment of Damages and Availability of Punitive Relief

Section 36 of the Competition Act creates a statutory cause of action to recover losses arising from breaches of the criminal provisions in Part VI of the Act, including price-fixing, bid-rigging, wage-fixing and deceptive marketing practices, as well as failures to comply with orders of the Competition Tribunal or a court. Plaintiffs may recover the amount of loss or damage proven, plus a portion of investigation and litigation costs that the court considers appropriate. Where there has been a prior criminal conviction, Section 36(2) provides prima facie proof of the underlying contravention, significantly easing the plaintiff’s evidentiary burden.

Section 36 does not permit recovery of exemplary or punitive damages. However, in Microsoft Corp. v Pro-Sys Consultants Ltd., the Supreme Court of Canada confirmed that Section 36 does not displace concurrent common law or equitable causes of action arising from the same conduct. Plaintiffs may therefore pursue claims such as civil conspiracy, unlawful interference with economic relations, or unjust enrichment alongside a Section 36 claim. As a result, punitive damages may be available where the facts support an independent common law cause of action, even though such damages are not recoverable under Section 36 itself. A breach of the criminal conspiracy provision in Section 45 of the Competition Act may also satisfy the requirements of a civil conspiracy claim.

By contrast, breaches of the Act’s civil reviewable provisions generally do not give rise to damages claims, except where a Tribunal order has been violated. Recent amendments also allow private applicants before the Competition Tribunal to seek monetary recovery for certain civilly reviewable conduct, although this remedy is distinct from Section 36 damages.

Status of the “Passing-On” Defence in Canada

The passing-on defence is not available in Canadian antitrust litigation.

Interest on Damages

The availability and calculation of interest in Canadian antitrust litigation depend on the forum in which relief is sought and the nature of the claim. Interest is generally governed by the procedural law of the court or tribunal hearing the matter. Most provinces allow for pre- and post-judgment interests at posted rates updated each quarter.

The same approach applies to claims arising from a failure to comply with an order of the Competition Tribunal or a court under Section 36(1)(b). Courts retain discretion to vary the statutory rate where warranted by the circumstances.

For private applications before the Competition Tribunal relating to civil reviewable conduct, the monetary recovery regime that came into force on 20 June 2025 is distinct from Section 36 damages. The Tribunal may order payment of an amount not exceeding the value of the benefit derived from the anti-competitive conduct and direct its distribution among similarly affected persons. However, the legislation does not currently prescribe a specific statutory interest formula for such awards, and the Tribunal’s approach to interest remains largely undeveloped given the recent introduction of the remedy.

Joint and Several Liability, Criminal Provisions

Whether liability is joint and several in Canadian antitrust litigation remains unsettled. Section 36 of the Competition Act permits a person who has suffered loss or damage as a result of conduct contrary to Part VI to recover damages from the person who engaged in the impugned conduct, but it does not expressly address the allocation of liability among multiple defendants.

Parliament previously considered codifying joint and several liability. However, the relevant provision in the proposed act was repealed before coming into force and therefore does not govern civil actions today.

Absent legislative guidance or definitive appellate authority, the issue remains open, although courts may ultimately draw upon broader Canadian principles governing concurrent wrongdoing, which generally recognise joint and several liability. This would allow a claimant to recover all of its damages from any one defendant, leaving the defendants to resolve issues of apportionment amongst themselves.

Joint and Several Liability, Civil Provisions

In the civil reviewable practices context, the Competition Act is largely silent on the allocation of liability among multiple respondents. As a result, courts may look to provincial law for guidance on issues of fault allocation and recovery. For example, Section 1 of Ontario’s Negligence Act provides that where damages have been caused by the fault or negligence of two or more persons, the persons are jointly and severally liable to the injured party for the full amount of the loss.

Although the application of provincial liability rules to proceedings brought under the federal Competition Act could theoretically raise federalism concerns, particularly if a provincial rule were found to conflict with the federal statutory scheme, modern Canadian division of powers jurisprudence generally favours the concurrent operation of federal and provincial laws wherever possible. Accordingly, absent a genuine operational conflict, provincial rules respecting parties who are jointly and severally liable would likely continue to apply. This may become particularly relevant as the expanded private access regime under Section 103.1 of the Competition Act gives rise to an increasing number of civil applications involving multiple respondents.

Immunity and Leniency Applicants

The Competition Act does not currently limit the civil liability of immunity or leniency applicants. Consequently, parties that co-operate with the Competition Bureau may nonetheless remain defendants in follow-on damages actions under Section 36 and may be exposed to the same civil remedies as other participants in the alleged conduct.

Claiming Contributions From Third Parties

Canadian antitrust defendants may seek contribution and indemnity from other parties alleged to have participated in the impugned conduct. The Competition Act does not contain an express contribution regime. As a result, such claims typically rely on common law principles governing concurrent wrongdoing.

Procedurally, a defendant may commence a third-party claim against a non-party or a cross-claim against a co-defendant under the applicable rules of civil procedure.

Injunctive relief is available in common law court proceedings.

The Competition Tribunal may also grant injunctive relief under Section 104 of the Competition Act in civil matters, including merger and non-merger reviewable practices cases, pending the determination of the underlying application. The Tribunal may grant any interim order it considers appropriate, having regard to the principles ordinarily applied by Canadian courts when granting interlocutory injunctions.

Test for Granting an Injunction

Canadian courts and the Competition Tribunal follow the principles governing interlocutory injunctions established by the Supreme Court of Canada in RJR-MacDonald Inc v Canada (Attorney General). In Canada (Commissioner of Competition) v Secure Energy Services Inc., the Tribunal confirmed that an applicant under Section 104 of the Competition Act must generally establish: (i) a serious issue to be tried; (ii) irreparable harm if relief is refused; and (iii) that the balance of convenience favours granting the requested relief. Where the relief sought is mandatory rather than prohibitory, a stronger prima facie case may be required.

Procedure, Timing and Notice

An application for injunctive relief is brought before the Competition Tribunal after the filing of a substantive application under the relevant provision of the Competition Act. Section 104(1.1) further provides that where an interim order is sought in respect of a proposed merger, the transaction cannot be completed until the application is determined. The Tribunal has indicated that urgent Section 104 applications should ordinarily be heard within approximately one week where a transaction is imminent.

Ex Parte Relief and Undertakings

The Competition Act also authorises certain forms of relief without notice. In particular, Section 100 permits the Commissioner to seek an interim order preventing completion of a proposed merger while the Bureau completes its inquiry, and Section 103.3 provides for ex parte interim orders in certain reviewable practices matters. As with other injunction proceedings brought before the Canadian courts, an applicant proceeding without notice is generally expected to make full and frank disclosure of all material facts. Unlike ordinary civil injunctions, the Competition Act does not expressly require the Commissioner to provide a cross-undertaking in damages where interim relief is granted but the underlying application ultimately fails.

Alternative dispute resolution mechanisms are available in Canadian competition law proceedings, but they are generally voluntary rather than mandatory.

Mediation Before the Competition Tribunal

For reviewable matters before the Competition Tribunal, parties may participate in a confidential mediation conducted by a judicial member of the Tribunal. Mediation is available in all contested Tribunal proceedings, including private access applications brought with leave under Section 103.1 of the Competition Act. Consistent with subsection 9(2) of the Competition Tribunal Act, the Tribunal encourages the informal and expeditious resolution of disputes where appropriate.

Mediation occurs only with the consent of all parties and may take place at any stage of the proceeding. Parties may seek to resolve the entire dispute or only specific issues. Where a settlement is reached, it is commonly formalised through a consent agreement registered under Sections 74.12 or 105 of the Competition Act.

Consent Agreements

In civil enforcement matters, parties may also resolve disputes through negotiated consent agreements with the Commissioner of Competition. Under Section 105 of the Competition Act, a consent agreement registered with the Tribunal has the same force and effect as a Tribunal order. This mechanism is frequently used to resolve reviewable conduct matters without a contested hearing.

Criminal Matters

ADR mechanisms are generally not used in criminal competition proceedings, such as cartel and bid-rigging prosecutions. Those matters proceed through the criminal justice system, although immunity and leniency programmes may facilitate negotiated resolutions with enforcement authorities.

Third-party litigation funding is available in Canadian competition proceedings, including private damages actions, competition class actions and proceedings before the Competition Tribunal. Although funding agreements were historically vulnerable to challenges based on the common law doctrines of maintenance and champerty, Canadian courts now frequently uphold such arrangements where they promote access to justice, do not provide the funder with excessive control over the litigation and do not otherwise undermine the administration of justice.

Litigation funding is most commonly used in private actions under Section 36 of the Competition Act, particularly cartel and bid-rigging class actions.

Costs awards in Canadian competition proceedings (especially class actions) depend on the jurisdiction. While some jurisdictions have a “loser pays” principle, other jurisdictions (eg, the Federal Court) operate on a presumptive no-costs basis.

Before the Competition Tribunal, Section 8.1(1) of the Competition Tribunal Act expressly authorises the Tribunal to award costs on an interim or final basis in accordance with the Federal Courts Rules.

The amount recoverable varies by jurisdiction and circumstances. In Ontario, successful parties typically recover partial indemnity costs, often in the range of 40-60% of actual legal fees. Rule 49 of the Rules of Civil Procedure may result in enhanced cost consequences where a party rejects a settlement offer and fails to obtain a more favourable result at trial.

Security for Costs

Defendants may seek security for costs in civil competition proceedings. In the Federal Court, Rule 416(1) of the Federal Courts Rules authorises the Court to order security where, among other things, the plaintiff is ordinarily resident outside Canada, is a corporation with insufficient assets in Canada to satisfy a costs award, has unpaid costs orders, or where there is reason to believe the proceeding is frivolous and vexatious and the plaintiff lacks sufficient assets to satisfy a costs award. Rule 417 permits the Court to refuse security where an impecunious plaintiff demonstrates that its claim has merit.

In practice, security is commonly provided by payment into court, a letter of credit or other court-approved security. Under Rule 416(3), the proceeding may be stayed until the ordered security is furnished.

Appeals

Appeals are available in Canadian competition proceedings. Decisions and orders of the Competition Tribunal may be appealed to the Federal Court of Appeal pursuant to Section 13 of the Competition Tribunal Act. Appeals on questions of law may be brought as of right, while appeals on questions of fact require leave of the Federal Court of Appeal. A further appeal may be brought to the Supreme Court of Canada with leave.

Decisions of the Commissioner of Competition that are amenable to judicial review are generally reviewed by the Federal Court under Section 18.1 of the Federal Courts Act.

Competition class actions and criminal proceedings follow the ordinary appellate structure, with appeals proceeding through the relevant provincial or federal courts of appeal and, where leave is granted, to the Supreme Court of Canada.

Expanded Private Enforcement

Canadian antitrust litigation is expected to increase following the recent expansion of private access to the Competition Tribunal under Section 103.1 of the Competition Act. As of June 2025, private parties may seek leave to bring applications in respect of two additional categories of anti-competitive conduct under the Competition Act: civil anti-competitive agreements and civil deceptive marketing practices. The reforms also permit the Tribunal, in certain circumstances, to award an amount not exceeding the value of the benefit derived from the impugned conduct.

Zero-Priced Markets

An emerging challenge is the application of traditional competition law tools to zero-priced markets, where consumers do not pay a monetary price for a product or service and instead provide attention, personal data or other forms of value. Digital platforms, search engines and social media services frequently operate in such markets. A key unresolved question is how courts and competition authorities should apply the hypothetical monopolist test, which traditionally examines the effects of a small but significant non-transitory increase in price, where no monetary price exists. This issue is likely to drive further jurisprudential and potentially legislative developments.

Cross-Border Litigation

Canada’s mature class action regime and increasingly international competition enforcement environment are also likely to encourage more cross-border and multi-jurisdictional competition claims.