“ 10. It is true that in determining the application of the rule of res judicata the Court is not concerned with the correctness or otherwise of the earlier judgment. The matter in issue, if it is one purely of fact, decided-in the earlier proceeding by a competent court must in a subsequent litigation between the same parties be regarded as finally decided and cannot be, reopened. A mixed question of law and fact determined in the earlier proceeding between the same parties may not, for the same reason, be questioned in a subsequent proceeding between the same parties. But, where the decision is on a question law, i.e. the interpretation of a statute, it will be res judicata in a subsequent proceeding between the same parties where the cause of action is the same for the expression "the matter in issue" in S. 11 Code of Civil Procedure means the right litigated between the parties, i.e. the facts on which the right is claimed or denied and the law applicable to the determination of that issue. Where, however, the question is one purely of law and it relates to the jurisdiction of the Court or a decision of the Court sanctioning something which is illegal, by resort to the rule of res judicata a party affected by the decision will not be precluded from challenging the validity of that order under the rule of res judicata, for a rule of procedure cannot
