The Centre on Wednesday told the Supreme Court that its has been approved by experts and was not open to judicial review as it was a policy decision.

The government told a five-judge constitution bench headed by Chief Justice Dipak Misra which is examining the validity of and its enabling 2016 law that in a digital era, Aadhaar is the best way to prevent "money laundering and deliver subsidies and benefits".

"The policy decisions of the government approved by experts are not subject to judicial review," Attorney General K K Venugopal told the bench which also comprised justices A K Sikri, A M Khanwilkar, D Y Chandrachud and Ashok Bhushan.

Venugopal, in his day-long arguments, also referred to various reports including that of World Bank and said that they acknowledged that India has taken a step to give an identity to the "poorest of poor", which would finally help in achieving the task of financial inclusion of all.

The top law officer said that that the development will slow down if there was judicial review of every state action and "courts should not interfere in matters of technical expertise".

The only duty of the court is to expound the language of the law and it may not decide whether a particular policy decision is fair or not, he said.

The bench asked Venugopal that the people, opposed to the scheme, say that it violated the doctrine of proportionality.

The satisfies the test of proportionality by showing a rational nexus between the means and the goal, he said, adding that all subsidies were part of right to life with dignity and would prevail over the right to privacy.

The State has a legitimate state interest in rolling out Aadhaar, he said.

On the issue of 16-digit virtual Aadhaar ID, Venugopal said that it is an excellent safety measure.

Is it the onus on the individual to generate and get a virtual ID, the bench then asked.

As Venugopal replied in affirmative, the bench asked as to whether 1.2 billion citizens can do it and said the Aadhaar may pass the test of "legitimate State interest", but the doctrine of proportionality has to be satisfied.

The bench said "biological attributes" are open-ended and the authorities may expand and include some more biometric features in the Aadhaar scheme in future and asked whether it would not amount to "excessive delegation of powers" by Parliament.

Blood, urine, DNA may be added, but that will be be subject to examination by the courts, just like right now the court is examining whether collection of fingerprints and Iris scans are a violation of privacy, Venugopal said.

The power of UIDAI to decide what is 'biological attributes" and the method of collecting it has to meet the test of proportionality, the bench said.

Venugopal said that Aadhaar has helped in curbing the leakages in the disbursal of benefits under welfare schemes.

The legitimate State interest runs through the entire Aadhaar Act and it has helped in the dissipation of subsidies, prevention of black money and money laundering by linking it with bank accounts, he said.

He referred to several judgments of the American Supreme Court which have upheld the fingerprint imaging for social security card.

However, the bench observed that the position taken by the European courts including by the German court was diametrically different to the position taken by US courts.

Would it be better not to refer to foreign court judgments as they may cause confusion, the bench asked.

The advancing of arguments remained inconclusive and would continue tomorrow.

Earlier, the Centre had said that the Aadhaar Act was a "fair and reasonable law" which complied with the tests prescribed by the historic verdict on the right to privacy.

The apex court had refused to pass an interim order extending the deadline of March 31 for linking of Aadhaar with the welfare schemes where benefits are transferred to citizens from the Consolidated Fund of India.

The bench is hearing on clutch of petitions challenging the constitutional validity of Aadhaar and its enabling 2016 law.