N.A. Khan vs Union Of India & Anr

The Supreme Court granted leave to appeal and examined the rejection of the appellant's promotion to a Group 'A' post by the Review Departmental Promotion Committee (DPC). The Court held that the principles of res judicata applied, as the appellant had previously challenged the DPC's decision before the Central Administrative Tribunal (CAT) and the High Court, which found that the DPC's assessment was proper. The Court upheld the High Court's dismissal of the writ petition, affirming that the DPC's findings were conclusive and that the appellant was not entitled to promotion due to insufficient vacancies and lower grading compared to others.