The deployment of surveillance vans near the student protest at Jantar Mantar has brought a growing policing practice into focus: the use of live video feeds and artificial intelligence (AI)-aided facial recognition to scan people gathered at a public demonstration.The Delhi Police says the system is being used to maintain law and order and identify known criminals. Protesters, however, say round-the-clock recording has created an atmosphere of intimidation, with several students covering their faces because they fear being profiled. The dispute has reached the Delhi High Court, raising questions over how facial recognition works and what safeguards govern its use.Across India, digital surveillance systems are increasingly becoming a key part of modern policing, with law enforcement agencies deploying networks of CCTV cameras, facial recognition technology, drone-based monitoring, automated number plate recognition systems and AI-powered video analytics.While authorities argue that such tools improve public safety and policing efficiency, their growing use has also raised concerns among civil liberties groups over privacy, proportionality, transparency, and the absence of a comprehensive legal framework governing state-sponsored surveillance.What surveillance technology has Delhi Police deployed?One vehicle at the site is a Mobile Command and Control Vehicle, where police personnel examine live CCTV feeds. The second is called Ikshana, a mobile surveillance van inducted ahead of the G20 Summit in Delhi in 2023.Ikshana has eight fixed cameras providing a 360-degree view. Its technology partner, CP Plus, says the vehicle supports face detection and recognition, number-plate recognition, traffic management, crowd monitoring, and on-the-spot video analytics. At Jantar Mantar, footage from cameras in the area is being run through facial recognition software, which places boxes around detected faces and compares them with images in police databases.Also read | Why some protesters at Jantar Mantar have their faces coveredA senior officer told The Indian Express that the purpose was to check whether the system flags anyone matching the police’s database of criminals. The Delhi Police has not publicly detailed the database’s size or composition, the software’s accuracy at the protest site, or the procedure followed after a possible match.Story continues below this adSome reports on social media have also said that the police are wearing AI-enabled smart glasses to surveil protesters. During the Republic Day celebrations earlier this year, the Delhi Police had used AI-enabled smart spectacles equipped with an integrated facial recognition system and thermal imaging technology. The product is developed by an Indian company called AjnaLens.The Delhi Police did not respond to queries on the issue.Facial recognition systems analyse a person’s facial features from an image or video, convert them into a unique digital template, and compare that template against images stored in a database. If the similarity score crosses a predefined threshold, the system flags a potential match for further verification. In response to a Right to Information (RTI) request in 2022, the Delhi Police had revealed that it considered a match to be “positive” if its system showed an accuracy rate of 80%.Also in Explained | Can police hide their identity during protests? What the law, court rulings sayThe result is not, by itself, proof of identity. Performance varies with the algorithm, camera angle, lighting, image quality, masks, and the database being searched. Testing by the US National Institute of Standards and Technology has found differences in error rates across demographic groups in many algorithms. Human verification, audit trails, and clearly defined thresholds are therefore important in policing.Why are protesters concerned?Story continues below this adStudents at Jantar Mantar said the cameras were changing how they participated in the protest. Some covered their faces despite wanting to display posters, while others feared that footage could reach families, educational institutions or future employers. This is often described as a chilling effect: people remain formally free to protest, but surveillance may deter them from exercising that right.Former JNU Students’ Union president Aishe Ghosh has challenged the monitoring in the Delhi High Court, alleging “continuous, indiscriminate and intrusive surveillance”, including videography and a surveillance tower. Her plea argues that it violates the rights to privacy, dignity, free speech, and peaceful assembly.NewsletterFollow our daily newsletter so you never miss anything important. On Wednesday, we answer readers' questions.SubscribeDuring a hearing in the matter on Monday (July 20), Solicitor General Tushar Mehta, representing the Delhi Police, said the videography was only for maintaining law and order and public safety, not snooping. The court asked whether Delhi Police had a standard operating procedure or standing order for handling protests in line with earlier Supreme Court directions.What does Indian law say?Facial images and digital templates linked to identifiable people fall within the broad definition of personal data under the Digital Personal Data Protection Act, 2023. Section 17 of the law, however, exempts several obligations when data is processed for preventing, detecting, investigating or prosecuting an offence. The Centre may also exempt notified state instrumentalities, including security forces like the Delhi Police, for reasons including state security and public order.Story continues below this adThe law does not lay down a dedicated framework for police facial recognition, including rules on watchlists, matching thresholds, independent audits, or specific retention periods. One officer said there were no fixed retention guidelines for the protest footage because it could be needed for a future investigation.The constitutional question is wider than data protection. The Supreme Court, in a landmark judgement in 2017, has recognised privacy as a fundamental right and held that restrictions must satisfy legality, necessity, and proportionality. The key issue is whether continuous identification of people at a peaceful protest is a narrowly tailored public safety measure, or a disproportionate intrusion that treats all participants as potential suspects.