Three school boards in which high school teachers are on strike suggest that while the law doesn't explicitly ban local strikes on provincial issues, that is its intent.

The Liberal government's new School Boards Collective Bargaining Act is coming under fire at the Ontario Labour Relations Board for not being sufficiently clear.

The school boards in the regions of Peel, Durham and the Sudbury-area Rainbow District are arguing at the labour board that strikes by high school teachers in their districts -- affecting more than 70,000 students -- are illegal.

This is the first round of bargaining since the new process was passed last year, separating negotiations into local and central talks, and the school boards allege the three local strikes are really about central issues, such as class sizes.

School board lawyer Michael Hines says the key sections of the act make distinctions between local and central processes, so the law would be "a mockery of itself" if it allowed employees to "start hopping the fence" on strikes.

The Ontario Secondary School Teachers' Federation says the strikes are not on central issues.

The Minister of Education has also asked a separate arm of the labour board to consider whether the students' school year is in jeopardy. Liz Sandals made the request Friday, but her spokeswoman was not able to say Wednesday when the Education Relations Commission would be meeting.

Sandals has not yet said if the province is considering back-to-work legislation.

Central talks between OSSTF and the province had been stalled for weeks, but resumed Wednesday with a new mediator.

High school teachers in Ottawa and Halton Region are set to begin an administrative strike Thursday.

They will partially withdraw services, which means teachers won't add comments to report cards or attend staff meetings or school board meetings, and will hold some picket lines over the lunch hour. Regular school operations will continue, as will field trips and extracurricular activities.

Elementary teachers across the province are staging a similar job action, withdrawing from administrative duties but continuing with classes and extracurriculars.