The Equal Opportunities Commission is considering whether to back a male nurse - who is challenging NHS pension rules which give female nurses a better deal on early retirement - in taking his case to the Court of Appeal.
William James Quirk lost his claim against Burton Hospitals trust and the health secretary at the employment appeal tribunal last month.
He claims that the rules, which allow both female and male nurses to retire at 55, but with reduced benefits for men only, breach article 119 of the European Community treaty, which requires equal pay for men and women.
The rules allow women to retire with full benefits, while men receive reduced benefits for the part of their service before 17 May 1990.
Mr Quirk has been employed in the NHS since 1963. A win for him would be expensive for the NHS, in the wake of successful equal-pay claims for speech therapists and backdated pension claims by part-timers.
Giving leave to take the case to the Appeal Court, the tribunal said the issue was one of general public importance, which 'affects a large number of workers in pensionable employment and involves very large sums of money'.
The case revolves around two lines of cases in the European Court of Justice, and hinges on whether Mr Quirk can be said to have been denied access to a scheme, or just treated differently with regard to the level of benefits he was entitled to. The tribunal held that he fell into the second category.
Until 1990, when the European Court of Justice decided that differential retirement ages were contrary to EU law, it was reasonable for employers to think it was lawful to have different entitlements for men and women.
So NHS pension rules which allowed men as well as women to take early retirement at 55, but allowed men to count only their pensionable employment from 17 May 1990 (the date of the Barber v Guardian Royal Exchange Assurance Group judgement) - while women could count all their pensionable employment - were permissible under EU law.