At least 10 countries that previously criminalised only male same-sex sexual conduct have recently expanded their criminal codes to encompass sexual conduct between women, groundbreaking research has discovered. 

A report by the Human Dignity Trust, Breaking the Silence: Criminalisation of Lesbians and Bisexual Woman and its Impacts finds that in a quarter of the countries in the world it is illegal to be a lesbian, with penalties ranging from imprisonment to death.

The potential for persecution is amplified by other laws which place women's human rights at risk, the study says. 

According to the trust, the criminalisation of lesbian sex is often an extension of 'indecency' laws inherited either directly or indirectly from Britain in the 19th or early 20th centuries. 'The continuing significance of British colonialism in the existence of these persecutory laws cannot be overstated,' the report states.

The criminalisation of women is 'on the whole, a more recent phenomenon', it says. Of the jurisdictions to have criminalised lesbian conduct through statute, 16 use ‘gross indecency’ or ‘serious indecency’ provisions, either expressly by reference to females or through the use of gender-neutral language.

'This demonstrates a trend away from the British origins of the concept of gross indecency established in 1885, which targeted only male same-sex sexual conduct.'

Countries that have amended their penal codes in this way include Trinidad and Tobago in 1986, Solomon Islands in 1990, Barbados in 1992, Sri Lanka in 1995, Botswana in 1998, Malaysia in 1998, The Gambia in 2005, Zambia in 2005 and Malawi in 2011.

The report also finds several of examples of countries that have criminalised lesbian conduct by other routes, including sharia. In Nigeria's Kano State an amendment to the State Penal Code in 2014 added a new offence of ‘lesbianism’, with a punishment of 14 years' imprisonment. Iran's Islamic penal code provides for a penalty of 100 lashes, or death for a fourth conviction.

In Yemen, premeditated homosexual acts between women carry a penalty of up to three years of imprisonment. 

The trust says its study fills a gap because much of the research, advocacy and legal discourse around the criminalisation and persecution of LGBT people worldwide has to date inadvertently focused on the situation of gay and bisexual men. 'This means that the unique situation of lesbians and bisexual women has not been properly addressed in legal responses to criminalisation.'

It adds that lesbians and bisexual women experience human rights violations in both similar and different ways or to different degrees than gay men, because of the intersection between their gender and sexual orientation.

'They can be particularly vulnerable to certain forms of control and abuse given the fact that women in many countries continue to be subordinated by male-dominated societies.'