The union representing striking postal workers lost a challenge to the constitutionality of back-to-work legislation passed in December.

The Canada Industrial Relations Board (CIRB) ruled against CUPW’s challenge to the order made by then-labour minister Steven MacKinnon.

On Dec. 13, 2024, MacKinnon issued a directive under section 107 of the Canada Labour Code to the CIRB regarding the labour dispute between CUPW and Canada Post.

MacKinnon directed the CIRB to assess how likely it would be for the two sides to reach a negotiated agreement by Dec. 31. If they deemed it unlikely, they were to order postal workers back to work until May 22, 2025.

The CIRB issued that order on Dec. 15.

CUPW argued that the section of the Labour Code used by MacKinnon gave both the minister and the CIRB the power to override protected collective bargaining rights, including the right to strike.

Section 107 gives the labour minister the authority to “do such things as to the Minister seem likely to maintain or secure industrial peace and to promote conditions favourable to the settlement of industrial disputes or differences…”

CUPW also argued the order violated its charter rights.

The CIRB said this is not the first time in recent years the federal labour minister has made such a referral, most recently with the CN Rail labour dispute. According to its decision, because the law in question was written after the charter, it’s presumed it doesn’t violate the charter.

The CIRB also held there are limits on its own ability to intervene or refuse to impose the minister’s direction. That power is held by the Federal Court of Canada. The CIRB can only exercise the powers given to it under the Labour Code.

The matter is also waiting on a hearing at the Federal Court. No decision has been made on that case at this time.