Discuss the doctrine of proportionality as evolved in *K.S. Puttaswamy v. Union of India* and its application to state use of surveillance technologies like facial recognition.

The nine-judge Bench in K.S. Puttaswamy v. Union of India (2017) held privacy to be a fundamental right flowing from Articles 14, 19 and 21, and made proportionality the constitutional yardstick for any state intrusion into it [1]. Surveillance technologies are the sharpest contemporary test of that yardstick.

The doctrine as evolved in Puttaswamy

• Legality — the intrusion must rest on a valid law, not executive discretion alone; the Court overruled M.P. Sharma and Kharak Singh on this count [1].
• Legitimate State aim — the restriction must serve a genuine public purpose such as security or crime control [1].
• Necessity and suitability — means must be rationally connected to the aim and be the least restrictive alternative available [1].
• Balancing with safeguards — the harm to the individual must not outweigh the public gain, and procedural guarantees against abuse must exist [1].

Application to facial recognition and surveillance

• Live constitutional test: the Supreme Court is examining the "proportionality" of Delhi Police's Facial Recognition System (FRS) used during the NEET-UG paper-leak protests of July 2026, the police affidavit defending it as "legitimate State interest" to identify "hardened criminals" [2].
• Legality gap: India has no dedicated facial-recognition statute; deployment rests on general policing powers, straining the first prong.
• Necessity: indiscriminate scanning of an entire protesting crowd to identify a few is arguably not the least intrusive means.
• Safeguards: petitioners allege retention of citizens' facial data by private entities, engaging purpose-limitation and storage-limitation duties under the Digital Personal Data Protection Act, 2023 [3].
• Wider costs: a chilling effect on peaceful assembly under Article 19(1)(b), and documented accuracy bias against women and minorities.

Proportionality is thus not an obstacle to technology but a discipline upon it. A statutory framework specifying authorisation, retention limits and independent oversight would let facial recognition serve legitimate policing while honouring the privacy that Puttaswamy placed at the heart of Article 21.