NEW DELHI: India's Supreme Court has ruled that citizens have a fundamental right to privacy, in a landmark judgement.
The judges ruled the right to privacy was "an intrinsic part of Article 21 that protects life and liberty".
The ruling has implications for the government's vast biometric ID scheme, covering access to benefits, bank accounts and payment of taxes.
Rights groups are concerned personal data could be misused. The authorities want registration to be compulsory.
The verdict overturns two previous rulings by the top court which said that privacy was not a fundamental right.
The nine-judge bench, comprising all the sitting judges in the Supreme Court was necessary because one of the earlier rulings made in 1954, was delivered by an eight-judge bench.
The Supreme Court verdict is a huge setback for the government which has insisted that privacy is not an inalienable fundamental right guaranteed under the constitution.
When the Aadhaar database was launched, the authorities said it would be a voluntary scheme which would help them weed out corruption while passing on welfare benefits to the most needy citizens.
But in the past couple of years, it has been made mandatory for filing tax returns, opening bank accounts, securing loans, buying and selling property or even making purchases of 50,000 rupees ($780; £610) and above.
The petitioners had said this would help the authorities create a comprehensive profile of a person's spending habits and expressed apprehension that this data could be misused by a government which does not believe in people's right to privacy.
During the hearing of the case, the government's lawyers had told the court that citizens did not have absolute right over their bodies which meant that people could be forced to give their biometrics.
Alarmed citizens can now breathe a sigh of relief - as one legal expert said, Thursday's order recognises the right of a citizen to be the master of his body and mind.