Discrimination in the workplace on the grounds of sexual orientation has been unlawful in the UK since 2003. For the purposes of survivors' pensions payable under occupational schemes, civil partners must be treated in the same way as spouses, but generally only in relation to pensionable service from 5 December 2005 (the date the Civil Partnership Act came into force).

The claimant in Walker v Innospec was a member of his employer's pension scheme, under the rules of which his surviving spouse would receive a pension on his death. At the date of his retirement, the claimant had been living with his male partner for 10 years; they registered a civil partnership in 2006 and have since married.  However, as all his service was completed before 5 December 2005, the pension scheme confirmed that they would not pay a surviving spouse's pension to his husband in the event of his death. He challenged this and, although the Employment Tribunal found in his favour, the EAT, and now the Court of Appeal, have reversed that decision, as well as deciding that the issue does not need to go to the European Court.

The claimant's entitlement to pension benefits was part of his pay, earned incrementally during his period of service. At the time when he earned that entitlement the discriminatory treatment was lawful. In line with the European law principle of "no retroactivity", it cannot later become unlawful retrospectively.  The exception in the Equality Act for service prior to December 2005 is clear. The fact that the government reviewed the differences in survivors' benefits in occupational pension schemes in the light of the same sex marriages legislation in 2013 and concluded that no changes were necessary is a clear indication, the Court said, that this is an issue of policy not interpretation.

A similar question in the joined case of O'Brien v Ministry of Justicewas whether the claimant, a part-time judge, was entitled to a pension calculated by reference to his service since he was first appointed (in 1978) or only from the date the Part-Time Workers Directive should have been implemented in the UK – 7 April 2000. Again, the Court of Appeal agreed with the EAT that rights cannot be backdated to a period before they existed in law. Prior to 7 April 2000 he had acquired no pension rights as a part-timer, and he could not do so retrospectively.