If the High Court bid is successful, gay and lesbian couples would be able to marry in one of the growing number of countries that offer same-sex ceremonies and have it legally recognised in Britain.
Celia Kitzinger, 48, and Sue Wilkinson, 51, will lodge their petition at the High Court on Friday and promise to take their fight to the European Court of Human Rights if they are unsuccessful.
They will be able to register their relationship under the new Civil Partnership Act, which comes into force in December. While it is not a marriage in name, it offers the same package of rights and responsibilities that a civil marriage does. But Ms Kitzinger and Ms Wilkinson believe they should be allowed to be married and will argue in the High Court that a failure to recognise the validity of their marriage constitutes a breach of their human rights.
The move raises the prospect of gay and lesbian couples taking "marriage holidays" abroad. Same-sex marriage was last month legalised across Canada. Three European countries - the Netherlands, Belgium and Spain - have also passed legislation allowing gay and lesbian couples to marry.
Ms Kitzinger, a sociology professor at York University, said: "Our relationship is not a civil partnership, it is a marriage. Any different-sex couple who did what we did would have had their marriage recognised. I feel insulted about being treated differently than a heterosexual couple."
The couple, who now live in Yorkshire, got married in British Columbia, Canada, in 2003. Ms Wilkinson, a psychology professor at Loughborough University, was living and working in Vancouver at the time. British Columbia was the first place in the world to allow same-sex citizens and non-citizens to marry.
Ms Kitzinger said they are in favour of the introduction of civil partnership, but believe both partnership and marriage should be available to different- and same-sex couples.
"Civil partnerships are a fabulous advance in human rights for same-sex couples," she said, "but it is a compromise. It is marriage in all but name. That name marks a symbolic difference between same-sex and different-sex couples. Marriage is the golden seal of a relationship. A civil partnership is not imbued with those same symbols."
A marriage that takes place overseas is recognised in Britain if it is legal, is recognised by the country in which it took place, and nothing in the country's law restricted either person's freedom to marry. Ms Kitzinger and Ms Wilkinson believe their marriage fulfils all these requirements and should, therefore, be legally recognised in Britain.
Peter Tatchell, the gay rights campaigner, said it would be "outrageous discrimination" if the courts refused to recognise the marriage of Ms Kitzinger and Ms Wilkinson. "The ban on same-sex marriage in the UK is institutional homophobia," he said. "All other marriages conducted lawfully abroad are recognised here. Why should same-sex marriage be an exception?"
The new civil partnership legislation has been criticised by some campaigners for not insisting that councils have to offer a ceremony. While the legislation ensures that local authorities are obliged to offer couples a registration service, two councils have already said they will not allow ceremonies.
Individual registrars opposed to civil partnership have threatened to refuse to preside over the ceremonies. Hundreds of hotels and banqueting halls are also refusing to allow gay and lesbian couples to hold a ceremony at their venue, according to "gay wedding" organisers.Reuse content