Supreme Court of India (Y. V. Chandrachud, C.J., with S. Murtaza Fazal Ali and E. S. Venkataramiah, JJ.), judgment of August 7, 1979, disposing Writ Petitions Nos. 159/77, 1211/77 and 3795/78 (Article 32) and Civil Appeal No. 1275/75 (special leave, from the Delhi High Court judgment/order dated 28-9-1973 in Civil Writs 536 and 537 of 1970). Engineers of the Roads Wing, Ministry of Shipping and Transport, appointed after interview by the U.P.S.C., acted contrary to the Central Engineering Service (Roads) Class I Recruitment Rules, 1959, whose permitted modes (rule 3: competitive examination, promotion, transfer; rule 4(b)) excluded mere interview; the amendment of August 2, 1966 adding rule 3(d)/Part VI (direct recruitment by selection through open advertisement) operated prospectively, and an illegality could not be regularised by rule-making under the proviso to Article 309, so the Delhi High Court had deemed these appointees holders of ex-cadre posts. Rules notified February 24, 1976 and a Notification of March 1, 1976 split the wing into the Central Engineering Service (Roads), Group 'A' and a closed Central Engineering Pool, Group 'A'; petitioners attacked the classification under Articles 14 and 16. Held: persons doing similar work cannot be classed apart merely because selected by different tests - no inferiority in ability, efficiency, qualifications or experience was alleged - yet, since some appointments violated the rules then in force, classification into cadre and ex-cadre categories had a valid basis, protected both classes, and the High Court's ex-cadre finding stood affirmed, barring any future action questioning the legality of those appointments. Operative order: rule 3/rule 19(2)-conforming officers belong to the regular cadre and may not be styled 'Pool'; others are ex-cadre and separately classifiable; the Central Government to scrutinise each Pool placement (representations by 1-10-1979; declaration by 1-1-1980), review wrongful placements, leave promotions before 31-5-1974 undisturbed and review later promotions to confer those due. Disposed of accordingly; no costs.