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ARTICLE · 28 JULY 2026

Not A Blanket Prohibition: Federal Replacement Worker Rules Clarified By CIRB

The Canadian Industrial Relations Board has issued its first interpretation of the new federal replacement worker provisions under Bill C-58, clarifying that the restrictions are categorical rather than absolute. In a landmark decision involving Montreal Gateway Terminals Partnership, the Board established key principles about when and how employers can use replacement workers during lawful strikes and lockouts, including critical distinctions about hiring dates, workplace geography, and employee classifica

CanadaEmployment and HR

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Introduction

The Canadian Industrial Relations Board (the “Board”) has released its first merits decision interpreting the new replacement worker provisions under the Canada Labour Code(the “Code”), which were introduced in 2025 through Bill C-58. The decision clarifies that the new rules do not create a blanket prohibition on the use of replacement workers in unionized federally regulated workplaces but instead restrict the use of specified categories of persons during lawful strikes and lockouts.

In Canadian Union of Public Employees, Local 4317 v. Montreal Gateway Terminals Partnership, 2026 CIRB 1225, the Canadian Union of Public Employees, Local 4317 (the “Union”) filed an unfair labour practice complaint with the Board alleging that Montreal Gateway Terminals Partnership (“MGTP”), the entity that operates the Port of Montreal, used replacement workers in violation of section 94(4) of the Code. The Board dismissed

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