A lesbian couple who have taken their landmark fight for legal recognition of their Canadian marriage all the way to the Supreme Court have outlined for the first time the significant financial and personal risks which their case has involved.

In a new book charting their life together, Katherine Zappone and Ann Louise Gilligan also reveal how Gilligan believes she was the victim of a breast cancer misdiagnosis in 1992, when four doctors told her that a small lump on her breast was not cancerous.

During an interview with the Sunday Tribune, the couple said if they lose their legal challenge, they could face a legal bill which could run into hundreds of thousands of euro.

While much depends on whether the court awards costs against them, the pair say they decided to pursue the case in the hope that justice "ultimately will prevail."

"We're either in pursuit of justice and equality or we're not. And the money can't be the prime consideration because if it is, it literally paralyses this kind of pursuit," Gilligan said.

They added that they are willing to consider taking their case to Europe, but expressed hope that the Supreme Court would rule in their favour. No date for their hearing has yet been set after the decision by the High Court to rule against their challenge in December 2006.

The book, entitled Our Lives Out Loud: In Pursuit of Justice and Equality also charts the various difficulties which the couple have faced during their careers, both at Trinity College Dublin in Zappone's case, and St Patrick's College Drumcondra, where Gilligan continues to work.

Both have been heavily involved in working with disadvantaged communities in the Dublin suburb of Tallaght.

In one chapter, entitled 'The Battle with the Bishops', Gilligan reveals how three successive archbishops of Dublin refused to discuss with her a decision not to approve her appointment to the post of head of the college's Department of Religious Studies, a role she eventually was permitted to take up.

Gilligan also describes her sense of "betrayal" by the first of these, the late Dermot Ryan, who had been a friend of her family for many years and had even lived at the back of her family home.

But she said she still lives under the threat that a controversial exemption in current equality legislation, which allows religious bodies to "opt out" of this legislation to preserve the religious ethos of an institution, could place her job at risk, if it is invoked.

"I don't think in my life, or my commitment, I have ever contravened the ethos of our college," she said.

"I'm sure it dwells somewhere in the membranes of one's brain that actually you know I could lose my job in the morning. I mean it's there somewhere… and it is most unfortunate that it is there."