"We do not decide constitutional issues by conducting a referendum. We follow the concept of constitutional morality and not majority morality. We don't go by majority morality, rather we go by constitutional morality," a five-judge bench headed by Chief Justice Dipak Misra told a lawyer favouring retention of section 377.

The bench, which also comprised Justices RF Nariman, AM Khanwilkar, DY Chandrachud and Indu Malhotra, made this categorical assertion when some lawyers, seeking upholding of section 377, said the petitioners, who were members of the LGBT community, constituted only 5-8 per cent of the country's total population.

Section 377 of Indian Penal Code (IPC) refers to 'unnatural offences' and says whoever voluntarily has carnal intercourse against the order of nature with any man, woman or animal, shall be punished with imprisonment for life, or with imprisonment of either description for a term which may extend to 10 years, and shall also be liable to pay a fine.

The top court said that notwithstanding the Centre's "concession" that the issue of decriminalisation of gay sex should be left to "the wisdom of the court", it would do a detailed analysis of the penal provision and its constitutionality.

The bench also made it clear that it was not concerned with bestiality, incest or other related issues, but only with the constitutional validity of Section 377 of IPC.

It said that over the years, an environment has been created in the Indian society which has led to such deep-rooted discrimination against the LGBTQ community.

The bench, which heard the lawyers opposing decriminalisation of gay sex, also rejected the "U-turn" charge made on Centre by advocate Manoj George, appearing for some churches on the issue of section 377.

When George said the Centre had taken a different stand in the high court on section 377 but had now taken a "U-turn" and left it to the top court's "wisdom", Justice Khanwilkar shot back saying he should not say it was a "U-turn" and even the verdict on fundamental right to privacy was a subsequent development.

Justice Chandrachud reminded the lawyer that the government had not filed an appeal against the 2009 Delhi high court verdict decriminalising section 377.

The CJI said that "despite giving a concession of leaving it to the wisdom of court, a detailed analysis of section 377 and its constitutional validity will be done".

"Even if Additional Solicitor General Tushar Mehta had argued for a whole day, it would not have made much difference. He is not a spokesperson of Parliament. He has to assist us on the constitutional aspect of section 377 of IPC," the CJI said.

At the outset, Justice Indu Malhotra observed that because of sexual orientation of LGBT community, their members have been discriminated in availing healthcare in semi-urban and rural areas.

"Family and society pressure forces gay persons to get married and that could be the reason for them to become bi-sexuals. Due to the criminality attached to same sex relationships, there are various other ramifications", she said.

Justice Malhotra said that 'Prakriti' (nature) and 'Vikriti' (abnormality) existed together in nature and there are hundreds of species which indulge in same sex intercourse.

To this, ASG Tushar Mehta intervened and said co-existence of Prakriti and Vikriti, which are referred to in various Hindu philosophical texts, are only related to philosophical and spiritual spheres and must not be dragged into the ambit of sexuality or homosexuality.

Senior advocate C U Singh, appearing for some mental health professionals, urged the court to say "something positive" on the lines of a doctrine against discrimination meted out to homosexuals.

Justice Chandrachud said that under Mental Healthcare Act, Parliament has prohibited any kind discrimination of anyone because of their sexual orientation.

Singh replied that unfortunately such non-discrimination because of sexual orientation has not been extended to all fields.

Senior advocate Ashok Desai, appearing for petitioner challenging section 377, said homosexuality has been part of India's ancient literature and culture and "hence not an alien to the Indian culture".

Senior advocate Krishnan Venugopal, representing another petitioner, said persons from LGBT community were denied their fundamental right to express their identity.

Suresh Kumar Koushal, on whose petition the apex court had set aside the 2009 verdict of apex court and upheld the validity of Section 377 in 2013, said that legalising gay sex could also encourage opening up of male prostitution outlets in the country.

The apex court clarified that it was not concerned with bestiality, incest or other related issues but only with the constitutional validity of Section 377 of IPC.

The bench asked the lawyers to file detailed written note of their submissions and said that arguments on the issue of section 377 should conclude on July 17.