Res judicata

Where res judicata applies, it may act as an estoppel, preventing a party from re-litigating a matter.

In order for this doctrine to apply, it must be shown:

a) that the same question has been previously decided;

b) that the decision was a judicial decision which is final;

c) that the parties to the previous decisions were the same as the parties to the proceeding in which the estoppel is raised.

At one time it was thought that if these conditions all applied, a party would have an absolute right to an order barring further litigation. This is no longer the case in Canada. Courts and tribunals have a residual discretion to refuse to apply the doctrine if it would be unfair.