As per case facts, petitioners and respondents were members of the Punjab Service of Engineers. Respondents were from Scheduled Castes, while petitioners were from the general category. The Punjab Government ... introduced reservation in promotions for Scheduled Castes and Backward Classes via a roster system. Petitioners challenged this policy after junior reserved category members were promoted, superseding senior general category colleagues. The question arose whether reserved category candidates appointed against general posts should be counted towards the overall reservation percentage, potentially making further reservations inoperative once the target is met, and if the roster system should continue indefinitely even after the full reservation quota is achieved in a cadre. Finally, the Supreme Court rejected the idea of counting reserved category candidates appointed in general posts towards the reservation quota. It clarified that the roster system should operate only until the prescribed reservation percentage for a cadre is fully achieved, after which it ceases. Subsequent vacancies are to be filled by members of the category to which the post originally belonged. This interpretation was made prospective.