Article 16(4) is a fundamental provision of the Indian Constitution, falling under the Right to Equality in Part III. It is an enabling provision that permits the State to make reservations in appointments or posts in favour of any backward class of citizens that is not adequately represented in the services under the State. This clause was included to ensure substantive equality by addressing the historical and social disadvantage faced by certain communities, making it a facet of the equality guaranteed by Article 16(1), not an exception to it.
The provision gained national prominence following the implementation of the recommendations of the Mandal Commission (constituted in 1979) for Other Backward Classes (OBCs). The Supreme Court's landmark judgment in Indra Sawhney v. Union of India in 1992 upheld the constitutional validity of reservation under Article 16(4) for OBCs, but ruled that the total reservation must not exceed a 50% ceiling limit and introduced the concept of the "creamy layer" exclusion.
In response to the Indra Sawhney judgment, which initially excluded reservation in promotions, the Constitution was amended. Article 16(4A) was inserted by the 77th Amendment Act, 1995, to allow reservation in matters of promotion for Scheduled Castes (SCs) and Scheduled Tribes (STs). Furthermore, the 81st Amendment Act, 2000, added Article 16(4B), which allows the State to treat unfilled reserved vacancies from a previous year as a separate class, effectively exempting them from the 50% ceiling in the year they are filled. More recently, Article 16(6) was added by the 103rd Constitutional Amendment to provide for reservation for the Economically Weaker Sections (EWS), expanding the overall framework of affirmative action under Article 16.