India’s top court has ruled unanimously that individual privacy is a fundamental right, in a blow to the government’s planned roll-out of the world’s largest biometric ID card program — known as Aadhaar.

Although prime minister Narendra Modi’s administration has long argued that privacy is not protected by the country’s constitution, the nine-member bench of India’s Supreme Court disagrees.

Chief justice JS Khehar said while reading out the verdict:

Right to privacy is an intrinsic part of right to life.

Tech giants operating in India will be affected by the court’s decision.

Search giant Google, Facebook and its WhatsApp messaging platform, and the likes of Apple and Uber, use the data of individual Indian users on a daily basis.

Samsung already sells devices in India with Aadhaar-compliant iris scanners embedded, while Microsoft integrated the biometrics into its Skype video-chatting service.

The judgement comes against the backdrop of a large multi-party case against the mandatory use of national identity cards.

Aadhaar is a 12-digit number provided to citizens after collecting their biometric information — finger prints and an iris scan — along with demographic details and a mobile phone number.

As well as concerns over data breaches, critics of Aadhaar say the ID cards could help to create a comprehensive profile of a person’s spending habits, their friends and acquaintances, and the property they own.

Over a billion Indians have already signed up for the ID cards, hailed by Modi as a way to help make the country a cashless society.

Enrollment in India’s ID card scheme is compulsory to complete income tax returns, operate bank accounts and for those eligible to to receive welfare benefits.

The legal validity of mandatory use of the Aadhaar program will now be scrutinized by a smaller bench.

Rahul Matthan, a privacy lawyer and partner at law firm Trilegal, said:

Now that the Supreme Court has ruled that the right to privacy is a fundamental right, the court can examine whether Aadhaar violates this fundamental right.