Matrix Chambers barrister Karon Monaghan is acting pro bono for human rights charity Liberty in an attempt to have a same-sex marriage recognised by the English courts.
Monaghan and Liberty will this week file an application in the Family Division of the High Court asking that the Canadian marriage of two university lecturers be recognised as a marriage by the court.
The case comes just months after the Civil Partnerships Act 2004 (CPA) received royal assent. Under the new legislation, same-sex couples are allowed to form a "civil partnership", affording them a number of legal rights and responsibilities. However, they are not yet permitted to marry in the same way that mixed-sex couples are.
In Canada, where Celia Kitzinger and Sue Wilkinson married in 2003, same-sex marriages are lawfully permitted. Traditionally, English law recognises legal marriages that take place abroad. Examples include those couples who choose to marry in balmier climates, as well as more unusual cases of polygamous weddings in places where they are permitted.
Kitzinger and Wilkinson's case is the first of its kind in the UK since the introduction of the CPA. The act currently accords a marriage of this kind recognition as a civil partnership.
But as Monaghan explained: "They're not happy to accept recognition of their marriage as a civil partnership, because they don't think that accords them equal status.
"The Human Rights Act [HRA] requires that equal recognition is shown to same-sex partnerships as opposite-sex partnerships."
She said that in Kitzinger's and Wilkinson's case, there appears to be no justification under the HRA that the marriage should not be recognised as such. If the couple wins their case, they will be accorded the same rights as any heterosexual couple who marry in England and Wales. "They hope that if it's successful, it will put pressure on the Government to consider whether or not civil partnership status affords true equality," Monaghan said.
This is not the first time that Monaghan has worked for Liberty or the first time she has defended such an issue. As a discrimination barrister, she has appeared in cases in a range of courts up to the European Court of Justice.
Those cases include last year's ultimately unsuccessful High Court petition by trade union Amicus and a number of other unions on behalf of their workers over the implementation of the European Employment Equality Regulations 2003, concerning the treatment of gay, lesbian and bisexual employees.