Here are the 10 points on this story:
In course of the hearing, Justice DY Chandrachud asked if a state could not "compel citizens to have Aadhaar in public interest". "Then it becomes a pervasive society," responded senior lawyer Shyam Divan. "We are governed by rule of law. You can't carve out an exception. If you compel, then it becomes a surveillance society... This has huge ramifications. There is no safe guard that my data is safe".
The petitioners alleged today that the Aadhaar data base "tends to terrorise citizens with the country becoming a totalitarian regime" as there is "no free consent in furnishing biometric information for Aadhaar".
Senior Supreme Court lawyer Shyam Divan, appearing for petitioners, told the five-judge Constitution bench that Aadhaar may cause death of citizens' civil rights. "A people's Constitution is being sought to be converted into a State's Constitution," he said.
The constitution bench headed by Chief Justice of India Dipak Misra is hearing 27 petitions including some filed way back in 2012, challenging various aspects of the Aadhaar programme. The other judges on the bench are Justices AK Sikri, AM Kanwilkar, DY Chandrachud and Ashok Bhushan.
Ahead of today's hearing, a group of private companies appealed to the Supreme Court seeking that the Aadhaar programme continue. The "intervention application" filed by the Digital Lenders Association of India (DLAI) has not been accepted so far. The application lists advantages offered by Aadhaar to digital companies, particularly the electronic know your customer feature which allows real-time verification of customers.
Nandan Nilekani, who executed the Aadhaar project, called the identification system an "empowering identity solution which neither compromises privacy nor excludes". "We're all in this together to achieve opportunity, development and empowerment of our billion people!" Mr Nilekani said in a tweet ahead of the hearing.
The court will also examine if it can scrutinise the decision of the Lok Sabha Speaker to specify a bill as a money bill as was done to the 2016 Aadhaar law. Because the Bill was a money bill, the Lok Sabha was empowered to vote down changes made by the Rajya Sabha. The judges, however, indicated that they did not think the court had this power.
Aadhaar was launched by the previous UPA in 2009-10 to reduce the government's subsidy bill and remove duplicates from the home ministry-driven national population register that was inspired by BJP patriarch LK Advani's identity card project.
After the BJP-led coalition came to power in 2014, Prime Minister Narendra Modi put the population register on hold and put his weight behind Aadhaar.
PM Modi also mandated that new-borns too be issued the number, not just children after they turn five. This would make the number, issued after a person's fingerprints and iris, a cradle to grave digital identity for every resident.
Supreme Court Imposes Fine Of Rs 5 Lakh For "Motivated" Plea Against Ex-Chief Justice's Appointment Dowry Cases: Top Court Modifies Order, Restores Power To Arrest Accused Section 377 Was Being Used As "Weapon Of Discrimination": Chief Justice Karnataka Chief Minister Siddaramaiah To Be Prosecuted In Land Scam Case Kolkata Rape-Murder Case Updates: Doctors On 24-Hour Nationwide Strike Video: Woman Tries To Jump Off Mumbai's Atal Setu, Saved By Driver, Cops "How I Wish To Be With You": Trapped Miner's Letter To Wife In 1902 Goes Viral IMF's Gita Gopinath Goes Bullish On India's Economic Growth For Debate Against Kamala Harris, Donald Trump Picks This Hindu American Track Latest News Live on NDTV.com and get news updates from India and around the world.