New Delhi,  The Supreme Court on Friday said the state governments are obligated to collect quantifiable data, on inadequacy of representation, before granting reservation in promotion to Scheduled Caste (SC) and Scheduled Tribe (ST) employees in government jobs.

A bench headed by Justice L.Nageswara Rao said the collection of quantifiable data is mandatory to evaluate the inadequacy of representation after completing a periodic review. The top court held that it cannot lay down any yardstick to determine inadequacy of representation.

The bench, also comprising Justices Sanjiv Khanna and B.R. Gavai, refused to water-down the criteria, which was laid down in the 2006 Constitution bench judgment in M. Nagaraj and in 2018 Jarnail Singh, to grant benefits of reservation in the promotions of SC and ST employees. The bench noted that the central government should determine the period review for providing reservation in promotion.

The top court observed that 'cadre' should be considered as a unit for collection for quantifiable data and the collection of quantifiable data is mandatory for assessment of inadequacy of representation after a periodic review is done. The review period should be determined by the Central government.

The top court said the Nagaraj judgment -- which laid down conditions like collections of quantifiable data, adequacy of representation, and overall impact on efficiency of administration -- will have prospective effect.

The apex court said B.K. Pavitra II judgment in 2019, was bad in law and contrary to M. Nagaraj judgment. In Pavitra II judgment, the top court upheld a 2018 law by Karnataka to provide consequential seniority to reserved category employees.

The top court will examine the contempt plea against the Centre for going ahead with promotion for hearing and it will take up matters connected with different state governments and the Central government petitions in the last week of February.