Natalie Bennett has said her party is “open to consultation” on the possibility of legalising polygamy and civil partnerships involving three or more people.
The Green Party leader was responding to a question from a man living with his two boyfriends in a polyamorous relationship in London on Friday.
Dr Redfern Jon Barrett, taking part in an event organised by Pink News, said people like himself in three-way relationships faced a “considerable amount of legal discrimination”.
He asked: “As someone living with his two boyfriends in a stable long-term relationship, I would like to know your stance is on polyamory rights. Is there room for Green support on group civil partnerships or marriages?”
Ms Bennett replied that although the Green Party “at present” has no specific policy on legal partnerships involving more than two people, members could develop one and vote for it to be introduced.
“We have led the way on many issues related to the liberalisation of legal status in adult consenting relationships, and we are open to further conversation and consultation on this issue,” she added.
Speaking at the launch of the party’s LGBTIQ manifesto in Soho later, she told journalists that she had “no personal view at all” on the issue but was prepared to listen to people’s views.
"What I said was we'd listen to the evidence on any issue, we believe in evidence-based policy-making,” she added.
"I don't think saying we will listen to the evidence is in any way outlandish.
"We have, for example, very bad laws that have created the war on drugs that comes from the result that we haven't had evidence-based policy-making.
"Caroline Lucas, the Green MP, put forward a call for the review of the 1971 drugs laws that have never been reviewed.
"Calling for evidence-based policy-making is a position that we should see in a great many more areas.”
The Greens' LGBTIQ rights manifesto includes a review of the 12-month blood donation ban for sexually active gay men and plans for more inclusive sex education from primary school.
Ms Bennett said there was still an "awful long way to go", adding that "homophobia, transphobia and biphobia are still too common in our society and too many people fear their impact in the workplace, in their schools and on the streets".
Opponents of gay marriage frequently raised the possibility of polygamy or even incest as the Marriage (Same Sex Couples) Act was being formulated.
It stipulates that the marriage of same sex “couples” is lawful. Polygamous marriages are not performed or recognised in the UK and anyone participating may be charged with the crime of bigamy.
The first same-sex marriages took place in England and Wales in March 2014 and Scotland followed in December.
Additional reporting by PA
The Independent has got together with May2015.com to produce a poll of polls that produces the most up-to-date data in as close to real time as possible.
Click the buttons below to explore how the main parties' fortunes have changed:
Join our commenting forum
Join thought-provoking conversations, follow other Independent readers and see their replies