Thousands of Montreal students could have an impromptu day off in a few weeks as their teachers stage a one-day strike.

The teachers, who are members of the Alliance des professeurs de Montréal and work mainly at Commission scolaire de Montréal (CSDM) schools, voted 77 per cent in favour of an illegal strike to be held May 1, International Workers' Day.

Approximately 110,000 students in the primary, secondary, adult and vocational sectors will be affected. The alliance has 8,800 members.

The members say they haven't been able to come to an agreement with the school board on work conditions such as the callback list, work-life balance and the lack of substitute teachers.

The teachers are covered by two collective agreements. One, which deals with issues including wages, allows the right to strike. It was ratified with the Quebec government in 2016 and is in effect until 2020.

But the other one, which covers the issues at hand, is signed between the school board and the union and doesn't include the right to strike.

Union ready to fight fines

Catherine Renaud, president of the alliance, acknowledged that the strike is illegal under Quebec's labour laws, but that they are ready to fight any fines if they are levied.

Catherine Renaud said the unions was time to negotiate with the school board, so they can properly discuss ways to improve conditions at the schools. (Radio-Canada) She said as far as they are concerned, the strike is legal, invoking the members' Charter rights of freedom of assembly and freedom of expression.

She called the school board's attitude at the negotiation table "despicable," saying the board is threatening members with the loss of their acquired rights, some of which they have had for decades, if the two sides don't reach an agreement by April 30.

"We keep asking more and more and more of our teachers to make sure students succeed, and we take away the means to make it happen."

School board president Catherine Harel Bourdon said the board plans to contact Quebec's labour tribunal to find out what its options are when it comes to the strike, but that the main priority is to reach a negotiated agreement with the teachers.

As for the lack of substitute teachers, Harel Bourdon acknowledged that the shortage is a problem across the province. That shortage makes it difficult, she said, to fulfil the teachers' demands for work-life balance.

"When we're asked to add days off to facilitate work-life balance, it takes substitute teachers for those days and with 8,500 teachers, that could make thousands, tens of thousands of replacement days, and right now we don't have the staff."