The case of Indra Sawhney v. Union of India (1992) was a landmark Supreme Court decision addressing the constitutionality of the 27% reservation for Other Backward Classes (OBCs) in government jobs and educational institutions, as recommended by the Mandal Commission. The challenge arose from concerns that such reservations might infringe upon the fundamental right to equality under the Indian Constitution.

• 1. Article 16(4) as an Exception to Article 16(1): Whether Article 16(4), which allows reservations for Backward Classes, is an exception to Article 16(1) and exhaustively covers the right to reservation in state services.
• 2. Meaning of Backward Class: The interpretation of Backward Class under Article 16(4), including whethercast alone can constitute a class.
• 3. Economic Criteria for Reservation: Whether reservation based solely on economic criteria can be considered under Article 16(1) if not covered by Article 16(4).
• 4. Extent of Reservation for Promotions: Whether reservations for Backward Classes apply only to initial appointments or extend to promotions as well.
• 5. Cap on Reservation Extent: Whether reservations under Article 16(4) or in combination with Article 16(1) can exceed the 50% cap established by previous judgments.

• 1. Article 16(4) and Article 16(1): It was held in this regard that “clause (4) of Article 16 is not an exception to clause (1) of Article 16. It is an instance of classification implicit in and permitted by clause (1)… it must be read along with and in harmony with clause (1).”
• 2. Meaning of "Backward Class": the Supreme Court firmly stated that the ‘class’ mentioned in Article 16(4) is a social class by looking at the context or purpose of the provision. The said provision does not have any qualifying words to ensure it is an inclusive provision unlike Article 15(4) because of which the word “backward classes” includes Scheduled Tribes, Scheduled Castes and all other backward classes of citizens including the socially and educationally backward classes.
• 3. Economic Criteria and Reservations: Reservations based solely on economic criteria cannot be covered under Article 16(4). Such reservations, if justified, would fall under Article 16(1) but still need to adhere to principles of equality.
• 4. Promotions and Reservations: The Court held that reservations for Backward Classes apply to initial appointments but denied reservation in promotions. The judgment clarified that promotions were not automatically covered under reservation policies.
• 5. Cap on Reservations: The Court upheld the 50% cap on total reservations established in the Balaji case. The ruling reinforced that the cumulative reservations, including for SCs, STs, and OBCs, should not exceed 50% of the posts.
• 6. The Court upheld the ceiling of the carry-forward rule for reservations, which limits the extent of reservations that can be carried forward to subsequent years if not filled and uphold Devadasan v. Union of India.The Court overruled Rangachar v. General Manager, Southern Railway (1972) and Akhil Bharatiya Soshit Karamchari Sangh (Railway) v. Union of India (1981) decisions that allowed reservations in promotions, reaffirming that such reservations were not permissible under the existing framework.

The judgment led to important constitutional amendments aimed at addressing the issues raised. The Seventy-Seventh Amendment Act of 1995 introduced Article 16(4A), which enabled reservations in promotions for Scheduled Castes (SCs) and Scheduled Tribes (STs). Following this, the Eighty-First Amendment Act of 2000 added Article 16(4B), which permitted the carry-forward of unfilled reserved vacancies for SCs and STs to subsequent years, thus providing a structured mechanism to address backlog in reservations.