Headed by the respected former chairman of IT giant Infosys, Nandan Nilekani, the scheme has been a model of unusual government efficiency. But the programme is now under threat from the Home Ministry, which has its own biometric database. It collects not only fingerprints and irises, but also sensitive information such as caste and religion, which it wants to use for security purposes.
A turf war between the Home Ministry and the UID Authority led to a compromise last week. The agencies agreed to share their data to avoid duplication. That allowed Mr Nilekani to collect another 400 million people on to his database. The government is providing more than US$1.5 billion (Dh5.5bn) to merge the databases.
It is unclear how all this information will be stored and shared, but it has done nothing to allay the fears of activists who foresaw the UID scheme turning into an Orwellian nightmare that could target, rather than help, India's poorest citizens.
"Every attempt at regulation in this country has failed," said Ms Ramanathan. "They say this data will not be abused, but how can we believe them?"