Can a unionized employee sue their employer for medical care for mental stress?

In Toronto Transit Commission v. Amalgamated Transit Union (2004), 132 L.A.C. (4th) 225, the Union argued that the employee suffered mental stress and ultimately had to have medical care. The employer argued that the arbitrator did not have jurisdiction to deal with the matter. The arbitrator said at p. 237: ... First, and at the very least, if management is not required to exercise its responsibilities reasonably, it must not abuse its authority and act in a manner that constitutes abuse or harassment of employees. Following O’Leary, even absent an express provision referring to managerial abuse or harassment, and apart from the management rights provision, I determine it is an implied term of the collective agreement that the work of a supervisor must be exercised in a non-abusive, non-harassing manner.