The surveillance controversy erupted during last week's student protest over exam paper leaks, when demonstrators posted pictures on social media of a mobile police surveillance van equipped with cameras on a telescopic mast providing a 360-degree view of the gathering.
One protester, student activist Aishe Ghosh, has asked the Delhi High Court to declare mass surveillance of protesters unconstitutional and direct the destruction of all personal data collected during the demonstration, as well as order the framing of guidelines on how surveillance technology can be used.
Ghosh is pressing on with the case even though the protest ended after Education Minister Dharmendra Pradhan resigned in a rare setback for Modi, who has since announced a panel to overhaul the cheating-prone exam system.
India has no law governing the use of facial recognition technology by police and surveillance at the main protest site in New Delhi was a breach of the law, activists say.
The government says such checks were legal and in the public interest to ensure law and order.
Modi's government has often been accused by opposition parties and digital rights advocates of expanding surveillance powers and tightly controlling digital communications. It has rejected such accusations, saying it only acts in the public interest.
During a hearing on Friday, Solicitor General Tushar Mehta defended the Indian police conduct, saying privacy claims at a public gathering were "absolutely necessary" and "in legitimate state interest."
In a brief hearing on Monday, judges heard arguments from Ghosh that intrusive mass surveillance of protesters was disproportionate, as she sought broader disclosures on the state's surveillance policies during protests.
The court will hear the matter on Tuesday.
Internet Freedom Foundation, a New Delhi-based digital advocacy group, wrote to Delhi's police commissioner on July 24 demanding the deletion of biometric data collected at the protest site.
Delhi police did not respond to a Reuters request for comment. In a post on social media platform X, the force said it had not "restricted anyone's freedom through the use of facial recognition technology".
"We need proportionality even if we are to claim national security risks. Accountability must flow both ways," said Akash Karmakar, a technology law partner at Indian law firm Panag & Babu.
