Gay sex is punishable by up to 10 years in jail.
Gay people in India face deep-rooted trauma and live in fear, the Supreme Court said on Thursday before deciding whether or not to scrap a colonial-era ban on homosexuality.
A five-judge bench made the comments while hearing a challenge to the ban, which the top court reinstated in 2013 after a four-year period of decriminalisation.
Gay sex is considered taboo by many in India, and despite opposition to lifting the ban from other petitioners and some lawmakers, activists were hopeful of a positive judgment after Thursday's hearing.
"(Homosexuality) is not an aberration, but a variation," said Justice Indu Malhotra. "Because of family pressures and societal pressures, they are forced to marry the opposite sex and it leads to bi-sexuality and other mental trauma."
The homosexuality law, commonly known as "Section 377", prohibits "carnal intercourse against the order of nature with any man, woman or animal" - which is widely interpreted to refer to homosexual sex. Gay sex is punishable by up to 10 years in jail.
A government lawyer said that it would leave it to "the wisdom" of the court to decide the constitutional validity of Section 377.
Lawyers for petitioners seeking to scrap the 157-year-old law have argued that sexual orientation is an intrinsic part of individual identity.
"This law has created utter chaos," Ashok Desai, a lawyer for one of the petitioners, told the court.
Mr Desai also argued that homosexuality was not alien to Indian cultural traditions, making a reference to a transgender character in the epic Mahabharata.
The court will resume hearing arguments from groups which support the homosexuality ban on Tuesday.
© Thomson Reuters 2018