Air Canada flight attendants waved flags and held signs reading “would you work for free?” as they picketed outside Toronto’s Pearson International Airport on Monday.

The Canadian Union of Public Employees contends that the government’s decision on Saturday to end the strike by taking it to binding arbitration is itself illegal and violates its members’ constitutional right to strike. It filed an application for an injunction to block the back to work order with the Federal Court of Canada over the weekend.