The SCs and STs had been provided reservation in promotions since 1955. However, the practice was discontinued following the judgement in the case of Indira Sawhney v/s Union of India,1992 wherein reservation in promotions was held unconstitutional by the Supreme Court.
Later the judgement was obliterated by the 77th Constitutional Amendment Act,1995 which inserted a new clause 4A in Article 16 for the purpose. Thereafter, 85th Constitutional Amendment Act,2001 was brought in which accorded consequential seniority to the SC and ST candidates promoted under the clause.
The validity of the two aforementioned Constitutional Amendments was challenged before the Supreme Court.The apex court in the M.Nagaraj v/s Union of India,2006 ruled that the concerned state will have to show in each case the existence of compelling reasons, namely, backwardness , inadequacy of representation and overall administrative efficiency(Article 335) before making provisions for reservation in promotion.
Recently a judgement came in case- Jarnail Singh vs Lachhmi Narain Gupta on 26 September, 2018. Now the Supreme court has further made it easy for the SC/ST candidates to grab reservation in promotion, it has removed two out of three criteria which were held in M.Nagraj case. Now the government is not required to collect the quantifiable data reflecting the backwardness among these communities, Also it is not required to check the efficiency of the department. But still the government will have to back the reservation to show the inadequate representation of SC/ST in the cadre.