India's top court has ruled adultery is no longer a crime, striking down a 158-year-old colonial-era law which it said treated women as male property.
Previously any man who had sex with a married woman, without the permission of her husband, had committed a crime.
A petitioner had challenged the law saying it was arbitrary and discriminated against men and women.
It is not clear how many men have been prosecuted under the law - there is no data available.
This is the second colonial-era law struck down by India's Supreme Court this month - it also overturned a 157-year-old law which effectively criminalised gay sex in India.
While reading out the judgement on adultery, Chief Justice Dipak Misra said that while it could be grounds for civil issues like divorce, "it cannot be a criminal offence".
Who challenged the law?
Last August, Joseph Shine, a 41-year-old Indian businessman living in Italy, petitioned the Supreme Court to strike down the law. He argued that it discriminated against men by only holding them liable for extra-marital relationships, while treating women like objects.
"Married women are not a special case for the purpose of prosecution for adultery. They are not in any way situated differently than men," his petition said.
The law, Mr Shine said, also "indirectly discriminates against women by holding an erroneous presumption that women are the property of men".
In his 45-page petition, Mr Shine liberally quotes from American poet Ralph Waldo Emerson, women rights activist Mary Wollstonecraft and former UN Secretary General Kofi Annan on gender equality and the rights of women.
However, India's ruling BJP government had opposed the petition, insisting that adultery should remain a criminal offence.
"Diluting adultery laws will impact the sanctity of marriages. Making adultery legal will hurt marriage bonds," a government counsel told the court, adding that "Indian ethos gives paramount importance to the institution and sanctity of marriage".
What did the adultery law say?
The law dictated that the woman could not be punished as an abettor. Instead, the man was considered to be a seducer.
It also did not allow women to file a complaint against an adulterous husband.
A man accused of adultery could be sent to a prison for a maximum of five years, made to pay a fine, or both.
And although there is no information on actual convictions under the law, Kaleeswaram Raj, a lawyer for the petitioner, said the adultery law was "often misused" by husbands during matrimonial disputes such as divorce, or civil cases relating to wives receiving maintenance.
"Men would often file criminal complaints against suspected or imagined men who they would allege were having affairs with their wives. These charges could never be proved, but ended up smearing the reputations of their estranged or divorced partners," he told the BBC.
Interestingly, Indian folklore and epics are full of stories about extra-marital love. Most love poems in Sanskrit, according to scholar J Moussaief Masson, are "about illicit love".
But Manusmriti, an ancient Hindu text, says: "If men persist in seeking intimate contact with other men's wives, the king should brand them with punishments that inspire terror and banish them".
What did the judges say?
All five Supreme Court judges hearing the case said the law was archaic, arbitrary and unconstitutional.
"Husband is not the master of wife. Women should be treated with equality along with men," Chief Justice Misra said.
Judge Rohinton Nariman said that "ancient notions of man being perpetrator and woman being victim no longer hold good".
Justice DY Chandrachud said the law "perpetuates subordinate status of women, denies dignity, sexual autonomy, is based on gender stereotypes".
He said the law sought to "control sexuality of woman (and) hits the autonomy and dignity of woman".
Critics have called the law "staggeringly sexist", "'crudely anti-woman'", and "'violative of the right to equality'".
"The legal system should not regulate whom one sleeps with," wrote Rashmi Kalia, who teaches law.
The main concern, according to the respected journal Economic and Political Weekly, is "not whether the expectations of fidelity in a marriage are right or wrong, or whether adultery denotes sexual freedom."
"It is whether the state can and should monitor a relationship between adults that is too complex, sensitive and individual for it to be capable of doing in a just manner," the journal wrote in a recent editorial.