What is the test for mootness?

Under the doctrine of mootness, a court may decline to decide a case which raises merely hypothetical or abstract questions. Mootness applies when the decision of the court will not have the effect of resolving a controversy which affects or might affect the rights of the litigants. However, even when a case is moot, a court may still decide to render judgment in certain circumstances. The leading decision concerning mootness is Borowski v. Canada (Attorney General), 1989 CanLII 123 (SCC), [1989] 1 S.C.R. 342.