A labor relations board declared a strike by Air Canada’s 10,000 flight attendants illegal on Monday and ordered their union to tell them to return to work by midday.

The presidents of two major Quebec unions fear workers in the province could soon face the same treatment as striking Air Canada flight attendants under a provincial law passed in May.

The current conflict at Air Canada ties into a much longer history of Canadian governments attempting to impose labour peace by clamping down on workers’ right to strike.