Preclusive effect refers to the legal doctrine that prevents a party from re-litigating an issue that has already been decided in a final judgment in a previous case. This principle ensures that once a dispute has been settled, the same parties cannot bring the same claims or issues again, promoting judicial efficiency and finality. It connects closely to concepts like motions for judgment as a matter of law and claim preclusion, as it reinforces the idea that once a court has ruled, that decision should carry weight in future proceedings.