Kuwait Court of Cassation principle number 733

Res judicata effect does not attach to conclusive judgments. Preparatory judgments. They do not acquire res judicata effect unless the judgment has determined, in its reasons or operative part, a segment of the dispute and an issue arising therefrom. Determination of a plea of lack of subject-matter jurisdiction acquires the force of res judicata even if contrary to public policy or issued by a court lacking jurisdictional authority.