This chapter the author demonstrates how the dominant theory of res judicata in civil law, developed by Giuseppe Chiovenda, is mistaken in its attempt to restrict res judicata to the adjudication of the request of relief by the plaintiff in final judgment. This theory artificially tried to remove issue determination from the scope of res judicata by treating it as mere logical reasoning leading to the decision on relief, which thus could be subject only to intraprocedural preclusion and not collateral preclusion. The reason that explains this mistaken theoretical endeavor is that issue determination cannot be reduced to simple logicism when an issue is fully litigated and determined, and that it matters beyond granting or denying relief in one suit, justifying the preclusion of further litigation on it by either party.