Aadhaar: Supreme Court held that Aadhaar would be voluntary, with an option to exit (File Photo)
The following is the chronology of events leading up to the Supreme Court on Wednesday declaring the centre's flagship Aadhaar scheme as constitutionally valid although it struck down some provisions including the linking of the biometric ID with bank accounts, mobile phones and school admissions, according to news agency Press Trust of India:
* January 2009: Planning Commission notification on UIDAI.
* 2010-2011: National Identification Authority of India Bill, 2010 introduced.
* November 2012: Retired Justice KS Puttaswamy and others file pleas in Supreme Court challenging validity of Aadhaar.
* November 2013: Supreme Court orders all states and Union Territories be impleaded as respondents.
* March 3, 2016: Aadhaar Bill, 2016 introduced in Lok Sabha; later passed as Money Bill.
* May 2017: Former Union minister and Congress leader Jairam Ramesh moves Supreme Court challenging the centre's decision to treat Aadhaar bill as a money bill.
* August 24, 2017: Supreme Court nine-judge bench rules that right to privacy is a fundamental right.
* December 15: Supreme Court extends deadline for mandatory linking of Aadhaar with various services and welfare schemes till March 31, 2018.
* January 17, 2018: Supreme Court five-judge bench begins hearing Aadhaar case.
* January 25: Supreme Court asks Chhattisgarh High Court to modify in 10 days its order directing all trial courts in the state to mandatorily accept copies of Aadhaar card for releasing an accused on bail.
* Febuary 19: Delhi BJP leader Ashwini Kumar Upadhyay seeks direction to Election Commission to take appropriate steps to implement an 'Aadhaar based election voting system'.
* February 21: Supreme Court says the alleged defect that citizens' biometric details under the Aadhaar scheme were being collected without any law, could be cured by subsequently bringing a statute.
* March 7: Supreme Court says Aadhaar number not mandatory for enrolment of students in all India exams.
* March 13: Supreme Court extends March 31 deadline of Aadhaar linking till it gives its order.
* March 22: UIDAI CEO says breaking the Aadhaar encryption may take "more than the age of the universe for the fastest computer on earth".
* March 28: Social activist Reshma Prasad seeks direction to the centre to create a separate third gender category option on PAN cards for transgenders.
* April 3: Centre tells Supreme Court that Aadhaar law is just, fair & reasonable.
* April 17: Supreme Court raises concerns that there is a threat of Aadhaar data misuse.
* April 25: Supreme Court questions centre on mandatory seeding of Aadhaar with mobile.
* May 10: Supreme Court reserves verdict.
* September 26: Supreme Court upholds constitutional validity of Aadhaar but strikes down certain provisions including its linking with bank accounts, mobile phones and school admissions.