During the lockdown in Hyderabad, activist S.Q. Masood was stopped on the street by police who asked him to remove his facial mask and then took his picture, giving no reason and ignoring his objections.

Worried about how the photographs would be used, Masood sent a legal notice to the city’s police chief. But after receiving no response, he filed suit last month over Telangana’s use of facial recognition systems — the first such case in India.

“Being Muslim and having worked with minority groups that are frequently targeted by the police, I’m concerned that my photo could be matched wrongly and that I could be harassed,” Masood, 38, told Reuters.

“It is also about my right to privacy, and my right to know why my photograph was taken, what it will be used for, who can access it, and how it’s protected. Everyone has a right to know this information,” he said.

Masood’s petition is seen as a test case as facial recognition systems are deployed nationwide, with digital rights activists saying they infringe privacy and other basic rights.

Facial recognition technology, which is increasingly used for everything from unlocking mobile phones to checking in at airports, uses artificial intelligence (AI) to match live images of a person for verification against a database of images.

The Centre, which is rolling out an automated facial recognition system nationwide — among the world’s largest — has said it is needed to bolster security in a severely under-policed country, to prevent crime and find missing children.

But there is little evidence that the technology reduces crime, critics say.

It also often fails to identify darker-skinned persons and women accurately, and its use is problematic in the absence of a data protection law in India, digital rights activists say.

“The technology is being rolled out at a very fast pace in India, on the premise that 24/7 surveillance is necessary and good for us,” said Anushka Jain from the Internet Freedom Foundation (IFF) digital rights group in Delhi.

“It’s important to challenge this notion, and a court case such as this will also help raise public awareness — most people are not even aware they are being surveilled,” said Jain, associate counsel at IFF, which helped prepare the petition.

CCTV cameras have become a common sight across the world, with some one billion forecast to be installed by the end of last year.

Alongside Chinese cities, Hyderabad and Delhi also have some of the world’s highest concentrations of CCTV cameras, according to website Comparitech.

Telangana has more than 600,000 cameras — most of them in the capital, Hyderabad — and the police can also use an application on their mobile phones and tablets to take photographs and match them on their database.

The state is “the most surveilled place in the world”, according to research published last year by Amnesty International, IFF and rights group Article 19, with systems deployed by the police, the election commission and others.

Hyderabad, which is home to the Indian offices of several global tech firms including Microsoft, Amazon and IBM, “is on the brink of becoming a total surveillance city”, said Matt Mahmoudi, Amnesty’s AI and Big Data researcher.

“It is almost impossible to walk down the street without risking exposure to facial recognition,” he said.

The rights of Muslims, Dalits, Adivasis, transgender people and other historically marginalised groups are at particular risk from such surveillance, activists say, with the systems already being used to police protests.

Masood’s lawsuit, which is listed for a hearing later this year, argues that the use of facial recognition in Telangana is “unconstitutional and illegal”. It says it is unnecessary, disproportionate and lacks safeguards to prevent misuse.

“This illegality cannot be cured or justified on the basis of its purported benefits in advancing law enforcement interests — under the guise of providing better policing... (when) these purported benefits are yet to be proven,” the petition says.

Hyderabad police say the technology has served as a “deterrent” and helped them catch criminals.

“We don’t infringe upon the privacy of any individual, as we are not barging into anybody’s house to take pictures,” said C.V. Anand, Hyderabad police commissioner.

“The technology is being used only to keep surveillance on criminals or suspected criminals,” he told reporters earlier this month in response to the petition.

In some parts of the world, there is growing pushback against the use of facial recognition.

In India, resistance from students, municipal workers and minority communities is growing as more services go online and government agencies and companies require personal data and location-tracking apps to undertake everyday tasks.

A planned data protection law gives wide exemptions to government agencies for the purposes of national security.

“It doesn’t talk about surveillance, which gathers data in secret and without consent, and it exempts government use, so it will fail to provide the sort of robust protections that are needed,” said Jain.

Masood, who is much more aware now of CCTV cameras and police officers taking photographs of residents in Hyderabad, wants others to recognise the dangers of facial recognition.

“The state has spent so much money on it, yet people have no idea how it works, how it can be misused, and how it abuses their privacy,” he said. “We are losing our fight to protect our privacy every day.”