Mohammad Naeem, a chaplain for the Prison Service, appeared in the Supreme Court on Monday as part of a legal battle which has lasted five years.
Naeem, supported by the union Prospect, had been working as a prison chaplain for ten years when he originally launched an employment tribunal in 2011.
He argued that he was being racially and religiously discriminated against during his work because he was being paid £5,000 less than his fellow Christian chaplains.
The tribunal ruled against him and after failing in two subsequent appeals, Naeem's case is now in the Supreme Court.
The Prison Service has argued throughout that chaplain pay is based on time served and, because Islamic chaplains have only been employed since the 2000s, they have had less time to progress up the pay ladder than Christian chaplains who've been a part of prisons for decades.
The Supreme Court judgement isn't expected until early 2017.
