Facial Recognition Technology (FRT), a form of automated identification based on biometric facial data, has become an important tool of State surveillance in modern times. Its use raises constitutional concerns because the collection, analysis and identification of a person’s face by State authorities may interfere with the right to privacy. This paper conducts a comparative constitutional study of India, the United Kingdom, Canada and South Africa to examine the permissible limits of State use of FRT. The study adopts a doctrinal and comparative methodology by analysing constitutional provisions, judicial decisions and relevant legislation in the four jurisdictions. The Indian analysis centres on Articles 14 and 21 of the Constitution and the Supreme Court’s ruling in Justice K.S. Puttaswamy (Retd.) v. Union of India [(2017) 10 SCC 1], which recognises privacy as a fundamental right and applies proportionality to evaluate State action. This framework is compared with Article 8 of the European Convention on Human Rights and R (Bridges) v. Chief Constable of South Wales Police [[2020] EWCA Civ 1058], Section 8 of the Canadian Charter of Rights and Freedoms, and Section 14 of the South African Constitution. The paper compares the requirements of legality, legitimate State purpose, necessity, proportionality, equality and safeguards against arbitrary surveillance. It finds that while all four jurisdictions recognise protection against State interference with privacy, they differ in constitutional basis, judicial oversight and legal safeguards for technologically assisted surveillance. The Indian constitutional framework provides a basis for scrutinising FRT, but clearer procedural protections and stricter legality and proportionality standards are necessary to define the permissible limits of State use of facial recognition.