What is mootness and what is the effect of mootness on a motion?

In Borowski v. Canada (Attorney General) (1989), 1 SCR, Mr. Justice Sopinka for the court discussed the concept of mootness at paragraph 15. The doctrine of mootness is an aspect of a general policy or practice that the court may decline to decide a case which raises a merely hypothetical or abstract question. The general principle applies when the decision of the court will not have the effect of resolving some controversy which affects, or may affect, the rights of the parties. If the decision of the court will have no practical effect on such rights, the court will decline to decide the case. This essential ingredient must be present not only when the action or proceeding is commenced, but at the time the court is called upon to reach a decision. Accordingly, if, subsequent to the initiation of the action or proceeding, events occur which affect the relationship of the parties so that no present live controversy exists which affects the rights of the parties, the case is said to be moot. The general policy or practice is enforced in moot cases unless the court exercises its discretion to depart from its policy or practice. The relevant factors relating to the exercise of the court's discretion are discussed hereinafter.