Special service rules govern seniority, and ad hoc officiation on a non-cadre post does not count toward seniority.

A special statutory service regime governing Development Authorities' seniority prevails over general seniority rules framed under Article 309, because general rules yield where a specific statutory framework already occupies the field. The applicable principle is generalia specialibus non derogant. Ad hoc promotion or officiation on a non-existent or non-cadre post does not count for inter se seniority unless the governing rules expressly permit it. Seniority is therefore determined by continuous service on similar posts from the date of initial appointment, not by a temporary elevation in a stop-gap capacity.

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Issues: (i) Whether the general seniority rules of 1991 could override the special seniority regime under the 1985 Centralised Service Rules governing the Development Authorities service; (ii) whether ad hoc promotion to a non-existent or non-cadre post could be counted for inter se seniority, or whether seniority had to be determined from the date of initial appointment on similar posts.

Issue (i): Whether the general seniority rules of 1991 could override the special seniority regime under the 1985 Centralised Service Rules governing the Development Authorities service.

Analysis: Rules made under the proviso to Article 309 of the Constitution operate only until provision is made by or under an Act or statutory rules governing the field. Where a statutory service regime already exists, the general rules yield to the special rules. The principle of generalia specialibus non derogant applies where two rules operate in the same field. The special rules framed under the Uttar Pradesh Urban Planning and Development Act, 1973 governed the Centralised Service, and the general seniority rules could not displace them.

Conclusion: The 1991 general seniority rules did not govern the service to the exclusion of the 1985 special rules.

Issue (ii): Whether ad hoc promotion to a non-existent or non-cadre post could be counted for inter se seniority, or whether seniority had to be determined from the date of initial appointment on similar posts.

Analysis: Seniority under the special rules depended on continuous length of service rendered on similar posts. The temporary or ad hoc elevation was to a post that was not available in the cadre and was not a legally relevant higher post for seniority purposes. Officiation in a stop-gap capacity on a non-cadre post does not confer seniority. Since the employees were ultimately absorbed on the same cadre post, the relevant criterion was the length of service from initial appointment on comparable posts, not the ad hoc promotion order.

Conclusion: The ad hoc promotion to the non-existent post did not count for seniority, and seniority was to be determined from the date of initial appointment on similar posts.

Final Conclusion: The challenge to the seniority determination failed, and the dismissal of the appeals followed on the basis that the respondents' seniority position was legally sustainable under the applicable special service rules.

Ratio Decidendi: Where a special statutory service rule governs seniority, general rules framed under Article 309 cannot override it, and ad hoc officiation on a non-cadre or non-existent post does not count towards seniority unless the governing rule expressly permits it.

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