Soon after the verdict came, Congress President Rahul Gandhi tweeted: "For Congress, Aadhaar was an instrument of empowerment. For the BJP, Aadhaar is a tool of oppression and surveillance. Thank you Supreme Court for supporting the Congress vision and protecting India."

Separately, the Congress party in a statement said the decision to strike down the Narendra Modi government's "surveillance tool" will put an end to the government's "abuse of power".

It said that through its judgment, the Supreme Court has firmly put an end to the "mass surveillance exercise" being carried out under the guise of Aadhaar and the "grotesque distortion of an idea conceived by the UPA".

Referring to the minority judgment by Justice D.Y. Chandrachud, the Congress said it is a scathing indictment of the government's clandestine and dishonest approach towards its parliamentary responsibilities.

The Communist Party of India-Marxist (CPI-M), too, hailed Justice Chandrachud's observation and reiterated that Aadhaar should not be mandatory for any welfare scheme.

The Left party pointed out that although the apex court has ruled that private companies cannot have access to the data, and Aadhaar is not required for bank accounts, mobile connections, admissions to educational institutions and entrance exams, private companies involved with the government would still have access to the Aadhaar data.

"While this may provide some protection to right to privacy, a major problem arises when this Central government has privatised and outsourced to private companies many government responsibilities.

"Such companies will have access to Aadhaar data. This is violative of the right to privacy -- a fundamental right -- ruled by the apex court itself," it said.

Welcoming the judgement, West Bengal Chief Minister Mamata Banerjee said it vindicated her stand.

"People should have some rights. If bank and mobile phones are linked to Aadhaar card then everything about the person will come into public domain. That this logic is correct and irrefutable has been proved today," Banerjee told the media in Milan, Italy.

BJP President Amit Shah also welcomed the apex court's verdict, albeit for a different reason.

"Today's Supreme Court Judgment is a strong validation of Aadhaar as an instrument of service delivery. It gives further impetus to empowering the poor by ensuring that they get their rights," Shah said in a tweet.

"Aadhaar under (Congress-led) UPA government was ‘Niradhaar' (baseless) and had no purpose. UPA spent thousands of crores to enrol people without any law or scrutiny. The Narendra Modi government gave it a strong legal backing and integrated it in service delivery. This ensured savings of Rs 90,000 crore and benefited the poor," Shah said.

The BJP called the verdict as "big victory for Modi government".

"We see this as a big victory of the pro-poor Modi government," BJP's national spokesperson Sambit Patra told the media.