Aadhaar is a unique 12-digit identity number issued to all Indian residents based on their biometric and demographic data. The data are compiled by the Unique Identification Authority of India (UIDAI), a statutory authority established in January 2009 by the Government of India, under the Ministry of Electronics and Information Technology, in accordance with the provisions of the Aadhaar (Target Delivery of Financial and other Subsidies, benefits and services) Act of 2016.
Aadhaar is the world's largest biometric identification system with more than 1,171 million enrollees as of August 15, 2017. As of this date, more than 99% of Indians over 18 years of age had been enrolled in Aadhaar . World Bank chief economist Paul Romer described Aadhar as "the most sophisticated identification program in the world."
Prior to the enactment of the Act, UIDAI served as an adjunct office of the Planning Commission (now NITI Aayog) since 28 January 2009. On March 3, 2016, a money law was introduced in Parliament to support to Aadhaar. On March 11, 2016, the Aadhaar (financial services and other subsidies, benefits and services) Act of 2016 was approved at Lok Sabha. On March 26, 2016, this Law was notified in the Gazette of India .
Aadhaar is not a proof of citizenship, and does not grant any right of domicile in India. In June 2017, the Ministry of Interior clarified that Aadhaar is not a valid identification document for Indians traveling to Nepal and Bhutan.
As of April 2017, a Supreme Court Constitution Court of India is considering the legal validity of Aadhaar's right to privacy grounds. On September 23, 2013, the Supreme Court issued an interim order stating that "no one should suffer for not obtaining Aadhaar," since the government can not deny a service to a resident if it does not possess Aadhaar, since it is voluntary and not mandatory. In another interim order on 11 August 2015, the Supreme Court of India ruled that "UIDAI / Aadhaar shall not be used for any purpose other than PDS, kerosene and LPG distribution system" (order subsequently modified to include Mahatma Gandhi National Rural Employment Guarantee Plan, all kinds of pension plans, employee pension funds and Prime Minister Jan Dhan Yojana), and made it clear that even to make use of these facilities Aadhaar card will not be mandatory. On March 27, 2017, the Supreme Court stated that Aadhaar may not be obligatory to obtain benefits from social assistance plans, although it may be mandatory for other purposes (such as income tax returns, bank accounts, etc.). On June 9, 2017, the Supreme Court of India partially read a legal provision (Section 139AA of the Income Tax Act) that required an individual to bind his Aadhaar to file his tax returns. Some civil liberties groups, such as the Citizens' Forum for Civil Liberties and the Indian Social Action Forum (INSAF), have opposed the project for privacy reasons.