Judgment

WANCHOO, J.: This petition under Art. 32 of the Constitution is a sequel to the judgment of this Court in T. Devadasan v. Union of India, AIR 1964 SC 179. The petitioner was Assistant in Grade IV of the Central Secretariat Service. The next post which the petitioner could expect to get was of Section Officer (Assistant Superintendent). Recruitment to the post of Section Officer is made in the following manner :--

(i) 50 per cent by direct recruitment from those who obtain lower ranks in the Indian Administrative Service, etc., examinations.

(ii) 25 per cent by promotion from Grade IV on the basis of a departmental examination held at intervals by the Union Public Service Commission, and

(iii) 25 per cent by promotion from Grade IV on the basis of seniority cum-fitness. In February 1960 the Union Public Service Commission issued a notification to the effect that a limited competitive examination for promotion to the post of Section Officers would be held in June 1960. The notification further stated that reservation of 12 1/2 per cent of the available vacancies would be made for members of scheduled castes and 5 per cent for the members of scheduled tribes. The number of vacanc