Preamble values have guided the evolution of Article 14 (equality before law) from formal equality (treating likes alike) to substantive equality (addressing historical disadvantages through affirmative action) through cases like ______ (1992) upholding OBC reservations with creamy layer exclusion.

Equality jurisprudence evolution under Preamble guidance: (a) Formal equality: Early cases interpreted Article 14 as treating likes alike; classifications must be rational, based on intelligible differentia, (b) Substantive equality: Indra Sawhney (Mandal case, 1992): Upheld 27% OBC reservation with creamy layer exclusion; recognized historical disadvantage requires affirmative action to achieve real equality — Preamble equality requires addressing structural inequalities, not just formal neutrality, (c) Further evolution: (i) M. Nagaraj (2006): Reservation in promotions requires quantifiable data on backwardness, inadequacy of representation, administrative efficiency, (ii) Davinder Singh (2024): States can sub-classify SCs for equitable benefit distribution, (d) Preamble principle: Equality not uniformity; reasonable classification permitted to address substantive inequalities; dignity requires recognizing and remedying historical disadvantage, (e) Applications: (i) Reservation in education/employment, (ii) Gender justice measures (Vishaka, Shayara Bano), (iii) Disability rights (RPwD Act), (iv) LGBTQ+ protections (Navtej Singh Johar), (f) Illustrates transformative constitutionalism: Using constitutional provisions to advance substantive equality for marginalized groups, guided by Preamble values. Essential for UPSC Mains understanding of equality evolution.