Two Christians, who claim that they were fired because they wouldn’t work with gay couples, are appealing to the European Court of Human Rights in Strasbourg.
Lillian Ladele and Gary McFarlane both refused to work with same-sex couples because of their Christian faith.
They were subsequently fired and say it was an act of discrimination.
A change in her working conditions meant she was unable to swap civil partnership duties with her colleagues and so was, she argues, forced to choose between her religion and her job.
In July 2008, an employment court ruled that Miss Ladele had been harassed at work when she was accused of being homophobic.
However, in December 2008 the Employment Appeal Tribunal overruled the court, and this was later upheld by the Court of Appeals in 2009.
Although the 51-year-old is reported to have never refused counselling in person to a same-sex couple, according to the charity Christian Concern, he did bring the issue up with his managers and was dismissed in 2008 for gross misconduct.
Since then the courts have consistently dismissed Mr McFarlane’s case.
The pair have joined two other Christians who felt they were discriminated against because of their faith.
Nadia Eweida and Shirley Chaplin both felt they suffered discrimination for wearing a cross around their necks.
A verdict by the European Court of Human Rights is not expected for several weeks.