Civil P.C. (5 of 1908) , S.11— Execution proceedings - Constructive res judicata - Applicability -- Contention as to jurisdiction not raised in execution proceedings - Contention cannot be raised later at same stage of execution. Where at a particular stage of the execution proceedings, a contention that the decree is a nullity as the Court that passed it had no jurisdiction, is not raised, that contention cannot be raised later at the same stage of the execution proceedings. It is barred on the principle of constructive res judicata. In the eye of the law, it must be deemed that judgment-debtor raised the question of jurisdiction and that question was decided against him: It is well settled that S.11, Civil P.C. is not exhaustive and the principle of res judicata applies to proceedings other than suits referred to in S.11. It is equally well settled that the principle of res judicata applies to execution proceedings. The principle underlying res judicata is that there must be a finality to litigation and the finality is arrived at not only by Court actually deciding the issue but also by the law taking the view that the Court has constructively decided the issue. The law does not only not permit a party to raise a contention which has already been decided, but it also prevents a party from raising a contention which he could have raised and h....