The union filed a grievance alleging the employer failed to provide certain benefit coverage, relying on the clear language of the collective agreement.
The employer asserted the language was ambiguous and sought to rely on extrinsic evidence of negotiating history and past practice.
The parties disputed who should call such evidence first.
The arbitrator ruled that because the union relied solely on the clear language of the agreement to meet its onus, the employer, as the party asserting the ambiguity as a defence, must call its extrinsic evidence first.
The union would then be entitled to call reply evidence.