K.S. Puttaswamy v. Union of India (2017)

K.S. Puttaswamy v. Union of India arose from a writ petition filed in 2012 by Justice K.S. Puttaswamy, a retired judge of the Karnataka High Court, challenging the constitutional validity of the Aadhaar biometric identification scheme administered by the Unique Identification Authority of India. The Attorney General defended Aadhaar by invoking two old precedents—M.P. Sharma v. Satish Chandra (1954), decided by an eight-judge bench, and Kharak Singh v. State of Uttar Pradesh (1962), decided by six judges—both of which had suggested that the Constitution contained no guaranteed right to privacy. Because those rulings emanated from larger benches, a smaller bench hearing the Aadhaar challenge could not overrule them, so the matter was referred to a nine-judge Constitution Bench expressly to settle whether privacy is a fundamental right. On 24 August 2017 that bench delivered a unanimous verdict in Justice K.S. Puttaswamy (Retd.) v. Union of India, reported at (2017) 10 SCC 1.

The procedural mechanics of the case turned on the doctrine of binding precedent under Article 141 of the Constitution, which makes the law declared by the Supreme Court binding on all courts within India. A bench cannot overrule a co-equal or larger earlier bench; only a numerically larger bench can do so. Since M.P. Sharma commanded eight judges, the reference bench had to be at least nine. The Chief Justice of India, J.S. Khehar, constituted the nine-judge bench, which heard arguments over six days in July 2017. Six separate but concurring opinions were authored, with the plurality written by Justice D.Y. Chandrachud on behalf of himself and three colleagues. The bench framed the single question narrowly—does the Constitution guarantee a right to privacy—and deferred the substantive validity of Aadhaar itself to a subsequent five-judge bench.

The court located the right to privacy primarily within Article 21, which protects life and personal liberty, while holding that privacy also runs as a thread through the freedoms in Article 19 and the equality guarantee in Article 14. It expressly overruled M.P. Sharma and Kharak Singh to the extent they denied a privacy right. Crucially, the judgment held that privacy is not an absolute right; the state may intrude upon it only by satisfying a three-fold test of proportionality: first, the existence of a law (legality); second, a legitimate state aim (need); and third, a rational nexus between the measure and the object, with the least intrusive means adopted (proportionality in the strict sense). Justice Chandrachud, in a striking passage, also expressly disapproved the majority reasoning in ADM Jabalpur v. Shivkant Shukla (1976), the Emergency-era Habeas Corpus case that had subordinated fundamental rights to executive suspension.

The doctrinal consequences materialised rapidly in subsequent litigation across the Supreme Court's benches in New Delhi. In Navtej Singh Johar v. Union of India (2018), the court relied on Puttaswamy to read down Section 377 of the Indian Penal Code and decriminalise consensual same-sex relations. In Joseph Shine v. Union of India (2018), it struck down the adultery offence under Section 497. The Aadhaar question itself returned to a five-judge bench, which in Puttaswamy II (2018) upheld the Aadhaar Act of 2016 in substantial part while striking down Section 57's expansion of Aadhaar to private commercial use. The judgment also catalysed the legislative process culminating in the Digital Personal Data Protection Act, 2023, enacted by Parliament after the Justice B.N. Srikrishna Committee report of 2018.

Puttaswamy is distinct from a data-protection statute, which it is not: the judgment created a constitutional foundation rather than an operative regulatory regime, leaving the design of a data-protection law to the legislature. It is also distinct from the basic structure doctrine established in Kesavananda Bharati v. State of Kerala (1973), which constrains Parliament's amending power; Puttaswamy instead concerns the interpretation of existing fundamental rights and their horizontal and vertical reach. Practitioners should not conflate the 2017 nine-judge ruling (on whether privacy exists as a right) with the 2018 five-judge Aadhaar judgment (on whether the scheme passes the test the 2017 bench laid down)—the two are routinely cited together but resolve different questions.

Controversy persists over the application of the proportionality test rather than its existence. Critics note that the Aadhaar five-judge majority in 2018, while invoking Puttaswamy's framework, was accused in Justice Chandrachud's lone dissent of applying it too deferentially to the state. The interception and surveillance architecture under Section 69 of the Information Technology Act, 2000, and the Telegraph Act provisions remain contested against the Puttaswamy standard, as do questions raised by the Pegasus spyware allegations that prompted a Supreme Court-appointed technical committee in 2021. The Digital Personal Data Protection Act, 2023, has itself drawn criticism for broad governmental exemptions that arguably sit uneasily with the proportionality requirement the judgment mandates.

For the working practitioner—whether a UPSC aspirant preparing General Studies Paper II, a desk officer assessing surveillance legislation, or a policy researcher mapping India's data governance—Puttaswamy is the indispensable reference point for any analysis of liberty, autonomy, and the state's informational power. It supplies the constitutional vocabulary (proportionality, legitimate aim, least restrictive means) now invoked in every Indian privacy, surveillance, and data-protection debate, and it aligns Indian jurisprudence with comparative standards drawn from the European Court of Human Rights and the German Federal Constitutional Court. Mastery of the judgment's reasoning, not merely its holding, is essential for credible engagement with contemporary Indian rights discourse.