Federal Update: Bill C-58 Restricts the Use of Replacement Workers in Federally Regulated Workplaces

On June 20, 2025, Bill C-58, An Act to amend the Canada Labour Code and the Industrial Relations Board Regulations came into force. Bill C-58 aims to strengthen protections for unionized workers by removing the right of employers to use replacement workers during strikes or lockouts.

Restricted Use of Replacement Workers

Bill C-58 specifically removes the right of employers to use the following people as replacement workers:

• anyone hired after the official notice to bargain was given;
• employees employed before the notice to bargain was given, unless they already worked at the specific location before bargaining started;
• contractors (unless the employer was using the contractor’s services before the notice to bargain was given and so long as the contractor only performs work in the same manner, to the same extent, and in the same circumstances as they did before the notice to bargain was given);
• volunteers, students, or the public; or
• bargaining unit members themselves (i.e., bargaining unit members cannot cross picket lines).

Despite these general restrictions, employers can use replacement workers in the following limited circumstances:

• to prevent threats to life, health, or public safety;
• to stop serious damage or destruction to property; or
• to prevent serious environmental harm to the employer’s property.

Even in these circumstances, employers must first offer the work to union members before using replacement workers.

Fines for breaching these restrictions can be up to $100,000 per day.

Maintenance of Activities Agreements

Bill C-58 also tightens rules around “maintenance of activities” agreements by requiring the employer and the union to clearly define what activities must be maintained before notice of a strike or lockout may occur. Parties must enter into these agreements within 15 days of delivery of the notice to bargain , and file these agreements with the Canadian Industrial Relations Board (“CIRB”) and the Minister of Labour. If the parties are unable to agree on what activities must be maintained, then they will be required to apply to the CIRB for a decision.

Bill C-58 only applies to federally regulated workplaces, such as airlines, postal services or telecommunications providers. Although Bill C-58 represents a significant change in the law of using replacement workers in the federal sphere, it does align more closely with existing provisions in British Columbia; BC regulated workforces already have similar constraints on the use of replacement workers under the BC Labour Relations Code.  

If you have any questions about this article, please contact your Harris lawyer.