Maneka Gandhi v. Union of India (1978) transformed Article 21 from a narrow procedural guarantee into a broad substantive right. The Supreme Court held that the procedure depriving a person of life or liberty must be fair, just, and reasonable — not merely a procedure prescribed by law. The ruling also established that Articles 14, 19, and 21 are interconnected and cannot be read in isolation. Later developments partially qualified but never fully reversed this expansive reading.

Before Maneka Gandhi, Article 21 was interpreted narrowly under A.K. Gopalan v. State of Madras (1950), where the majority held that each Fundamental Right operates in its own independent field. As long as a law provided a procedure for depriving personal liberty, Article 21 was satisfied — the fairness of that procedure was irrelevant.

Maneka Gandhi overturned this siloed reading. The Supreme Court held three critical things: First, the procedure established by law under Article 21 must satisfy the test of reasonableness — it cannot be arbitrary, fanciful, or oppressive. Second, Articles 14, 19, and 21 form a golden triangle and must be read together; a law restricting personal liberty must pass the tests of all three articles simultaneously. Third, the right to life is not merely the right to physical existence but includes the right to live with dignity.

This ruling opened the door to an explosion of rights implied under Article 21 — the right to education, health, livelihood, a clean environment, speedy trial, legal aid, and privacy (later crystallised in Puttaswamy 2017). The 'procedure established by law' phrase was effectively read to mean 'due process of law' in substance, approaching the American due process standard without formally adopting it.

For CLAT PG, the examiner tests whether aspirants understand the doctrinal shift: from Gopalan's compartmentalised reading to Maneka's integrated golden-triangle approach, and the downstream implications for rights jurisprudence.