Adultery is no longer a criminal offence in India, after the Supreme Court voted today to repeal a 158-year-old colonial-era ban on infidelity.

The five-judge panel were unanimous in their verdict, “calling the law archaic and saying that it violates Articles 14 and 21 of the Indian Constitution” - which guarantee equality before the law and personal liberty respectively, The Indian Express reports.

The ban had been decried as intrusive, outdated and based on a sexist paradigm in which “the man was considered to be a seducer”, says the BBC.

The verdict adds India to a growing list of countries scrapping historical legislation that put citizens’ sexual (mis)behaviour under the control of the courts.

The UN has issued numerous calls to governments to repeal laws that criminalise adultery, arguing that they are predominantly used to discriminate against women. “Provisions in penal codes often do not treat women and men equally and establish harsher rules and sanctions for women,” according to human rights expert Frances Raday.

The organisation also argues that the criminalisation of sexual relations between consenting adults is a violation of their right to privacy.

Ghosts of the past

Many European countries once had anti-adultery laws on the books, but most were repealed in the 1970s and 1980s. The last European nations to decriminalise infidelity were Austria, in 1997, and Romania, in 2006.

The story is similar in Latin America, which saw a flurry of decriminalisation in the 1990s.

In the US, however, adultery remains technically illegal in 21 states. In most states, including New York, cheating on your spouse is considered only a misdemeanour. But in Idaho, Massachusetts, Michigan, Oklahoma and Wisconsin, among others, it is a felony crime punishable by prison.

However, attempts to enforce historic anti-fornication laws are vanishingly rare.

The laws remain on the books largely due to inertia, says The New York Times. Getting rid of them would require politicians to vocally oppose them - something few are willing to do.

Additionally, “many like the idea of the criminal code serving as a kind of moral guide even if certain laws are almost never applied”, says the newspaper.

That certainly was not the case in South Korea, whose adultery laws still very much had teeth in the 21st century. Between 2008 and 2015, when adultery was finally decriminalised, more than 5,500 people were successfully prosecuted for cheating on their partner, CNN reports.

Elsewhere in East Asia, adultery remains illegal in Taiwan and the Philippines.

The Muslim world

Countries governed by Islamic law, including Saudi Arabia, Pakistan and Somalia, all strictly prohibit zina, or "fornication outside marriage". Prosecutions are common and punishment can include fines, arbitrary detention, imprisonment, flogging and in extreme cases, the death penalty. Women are overwhelmingly targeted.

Human rights organisations argue that in several Muslim nations, adultery laws are often used against women who have been raped. Under such legislation, the burden of proof is on the woman to provide evidence that she was assaulted.