Carers UK, which is naturally hailing the opinion as an early victory, estimates that there are 2.5 million working carers in the UK and that one in five carers give up work because of their caring responsibilities.

In this case, Ms Coleman claimed that she had been discriminated against because she is the primary carer for her disabled son. She alleged that the discriminatory treatment included refusing to allow her to return to her existing job after coming back from maternity leave; calling her “lazy” when she sought to take time off to care for her son; refusing to give her the same flexible working arrangements as her colleagues with non-disabled children; and alleging that she was using her child to manipulate her working conditions.

An ECJ decision in Ms Coleman’s favour could lead to a major extension of disability discrimination legislation by UK courts interpreting the Disability Discrimination Act 1995 in light of the ECJ ruling or, if this is not possible, by amendments to the legislation itself.

It’s easy to envisage circumstances where carers could claim discrimination. Derogatory comments from managers or colleagues if a carer is frequently off work to care for a disabled person would lead to harassment claims. With unlimited compensation for discrimination compared to caps in constructive dismissal claims, discrimination claims would be very attractive for carers who are forced to quit work to look after disabled relatives.

Interestingly, unlike the laws on race, religion or belief and sexual orientation discrimination, age discrimination legislation does not currently provide protection against associative discrimination. There is nothing in the opinion to suggest that its principles could not be extended to age discrimination. If age discrimination legislation was to be extended in this way, carers of elderly relatives could theoretically bring age discrimination claims.

The UK Government would have to rethink its approach to disability and age discrimination by association. In its consultation on the proposed Single Equality Act, it took the stance that disability and age legislation does not need to be extended to cover associative discrimination.

But let’s not jump too far ahead. The ECJ does not have to agree with the Advocate General that EU equality laws extend to discrimination as a result of association with a disabled people and, if it does agree, it may apply different reasoning.

Read the opinion in full on the ECJ website.