The International Longshore and Warehouse Union (ILWU) gave British Columbia, Canada port employers a 72-hour strike notice on Wednesday, just hours after the federal Labour Minister and Canada Industrial Relations Board (CIRB) declared the ILWU’s renewed strike efforts illegal.

The ILWU went back on the picket lines Tuesday after members refused to ratify a tentative agreement with the British Columbia Maritime Employers Association (BCMEA). The ILWU’s initial strike began on July 1 and workers stopped picketing on July 13 when the agreement was announced.

Canadian Minister of Labour Seamus O’Regan released the CIRB’s decision on Twitter, briefly adding, “This strike is illegal.”

According to the decision, the CIRB held a hearing on July 18 where the BCMEA argued that the ILWU was in violation of the Canadian Labour Code, which requires unions to provide employers with 72 hours’ notice before commencing strike action. The ILWU countered that their strike never ended and that they did not have to give notice.

The premiers of Saskatchewan and Alberta have called on Parliament to force ILWU members to return to work, citing damage to the Canadian economy. Parliament passed “back to work legislation” in 2021 to force striking Montreal port workers back to work.

Striking is a protected activity in Canada, with limitations. The Canadian Supreme Court ruled in 2015 that workers have a right to strike under Section 2(d) of the Canadian Charter of Rights and Freedoms, subject to “reasonable limits prescribed by law as can be demonstrably justified in a free and democratic society,” per Section 1.