"The Attorney General argued before us that the right to privacy must be forsaken in the interest of welfare entitlements provided by the State. In our view, the submission that the right to privacy is an elitist construct which stands apart from the needs and aspirations of the large majority constituting the rest of society, is unsustainable," a group of four judges said in their judgement, also observing, "This submission betrays a misunderstanding of the constitutional position."
The scrutiny of public affairs is founded upon the existence of freedom, the judges said, pointing out that the court has categorically rejected earlier "the theory that civil and political rights are subservient to socio-economic rights."
"The refrain that the poor need no civil and political rights and are concerned only with economic well-being has been utilised though history to wreak the most egregious violations of human rights," their judgement says.
The Supreme Court had set up the special bench after petitioners challenged the government's decision to make the use of Aadhaar cards compulsory for a growing number of services, including opening a bank account or paying taxes.
The Aadhaar biometric programme has recorded the fingerprints and iris scans of more than one billion citizens and petitioners have said that enforcing its use is an infringement of privacy, pointing out that it was originally presented as a purely voluntary programme that offered to provide every Indian with an identity card.
The government argued that citizens cannot expect an absolute right to privacy, which is not explicitly mentioned in the Indian Constitution. Then Attorney general Mukul Rohatgi had rejected suggestions that people can refuse to provide their iris scans or fingerprints to the government, telling court "the concept of absolute right over one's body is a myth".
The government says the Aadhaar programme poses no threat to civil liberties, despite personal data being leaked in security breaches.
During the hearings, the Supreme Court bench recognised the risk of personal information being misused, and the challenge of protecting such private data in the internet era. But the judges also acknowledged there must be restrictions within reason on individual privacy.
"Any fundamental right is subject to reasonable restrictions by law. Whether the Aadhaar Act imposes unreasonable restrictions will have to be examined," said lawyer Prashant Bhushan after the judgement, stating that it will likely impact the Aadhaar programme.
The Supreme Court's ruling is "set back" for the government, said Mr Bhushan, who represents one of the petitioners.
Senior advocate Rakesh Dwiwedi, who argued for the Gujarat government, said the judgement is balanced and that the government's interests are protected.
The petitions challenging Aadhaar will now be referred to a separate five-judge bench.