A person is protected from discrimination if they are treated less favourably because they are married or in a civil partnership (Incidentally, a person cannot claim discrimination if they are treated less favourably because they are unmarried).
In Dunn v Institute of Cemetery and Crematorium Management (ICCM) the Employment Appeal Tribunal held that this includes protection from discrimination for being married to a particular person. So, as in this case, although the employer did not discriminate against married people generally, Mrs Dunn won her argument that she was treated less favourably specifically because of her marriage. The facts help to make the distinction clear.
Mrs Dunn had a number of problems with the ICCM which culminated in her resignation. There was also evidence of antipathy between the Chief Executive of ICCM and Mr Dunn, her husband. She claimed that she had been paid less sick pay than anyone else in her circumstances and that the treatment was on the ground of her marriage. A tribunal dismissed her claim, saying that the discrimination was not on the ground of Mrs Dunn’s status as a married person but because of the particular person to whom she was married.
The Employment Appeal Tribunal agreed with Mrs Dunn. Protection from discrimination is not only on the basis of 'marital status', but applies where the reason for treatment was that the person was married. This is consistent with an earlier case where a decision preventing a woman from working in the police division of which her husband was Commander, was held to be marital discrimination. The EAT considered that this was a marriage-specific reason as the wife's appointment would not have been blocked if her husband had not been head of that division.
Comment: Less favourable, marriage-specific, treatment is unlawful - a person who is married or in a civil partnership is protected from discrimination because of that relationship. However much you may have fallen out with one party to the marriage, you must not be influenced by that in your dealings with the other.