We also had the case of Nadia Eweida, the British Airways check-in worker who was not allowed to wear her crucifix outside her uniform. These cases have highlighted the difficult question of how far employers can dictate their employees’ appearance at work.

Here we aim to answer that question by looking at the employment claims which might arise from dress codes, and suggesting practical tips on how they can be avoided.

Employment claims
The main claims which might result from dress codes are sex discrimination, and race and religious discrimination.

Sex discrimination
Employers who set more relaxed rules for the appearance of their female employees than they do for their male staff, or vice versa, may face a sex discrimination claim. In the last few years a number of male employees of Jobcentre Plus have brought sex discrimination claims in relation to their employer’s dress code, which required all staff to dress in a ‘professional and business-like’ way, specifying that male employees had to wear a collar and tie and female employees had to dress appropriately and to a similar standard.

The male employees claimed that, by being required to wear collars and ties, they were treated less favourably than their female colleagues, who had no compulsory items of clothing. The claims did not succeed, because the dress code was equivalent for both sexes.

It was not relevant that the women were not required to wear compulsory items – what mattered was that the standards expected of men and women were broadly the same.

The key for employers is to ensure that the rules on what men and women can and cannot wear to work are equivalent and do not unfairly disadvantage either sex.

More difficult questions arise when it comes to hairstyles. Some employers might be happy for their female staff to wear long hair loose, but would not wish to see male employees do the same and would prefer them to cut it or tie it back.

A case on this point, some 10 years ago, suggested that an employer who required staff to have a conventionally smart appearance could justify asking a man to keep his hair short. But there is no guarantee that the same approach would be taken today.

Race and religion
Some employees have cultural or religious requirements that dictate aspects of their clothing or appearance. A dress code that does not accommodate these will amount to race or religious discrimination, unless it can be justified.

Examples of rules which may disadvantage employees of a certain race or religion include: 1) a requirement not to cover the face may adversely affect Muslim women who wish to wear a full veil; 2) stipulating that employees must wear conventional hairstyles could discriminate against Rastafarians who wear dreadlocks; 3) a ban on head gear may discriminate against Sikhs if they wear a turban; 4) requiring employees to be clean shaven may discriminate against Muslim employees who wear a beard; 5) preventing employees from wearing jewellery or tattoos could discriminate against employees from certain cultures or religions.

In order to defend discrimination claims, employers must show that the rule is justified, ie that it is necessary to achieve a legitimate aim. However, employers should accommodate cultural or religious requirements if they can do so without detracting from the aim behind the dress rules.

Interference
It will almost always be justifiable prevent an employee wearing an item which interferes with his or her ability to do the job effectively. Aishah Azmi’s claim for religious discrimination failed because her job involved teaching English and the school could show that the veil adversely affected the children’s ability to learn language skills.

The school’s case was strengthened by the fact that it did allow Ms Azmi to wear the veil in the classroom for a trial period, in order to see the effect it had.

Health and safety
Dress codes are sometimes introduced for health and safety reasons, which will usually justify any disadvantage to employees of a certain race or religion. For example, it would be justifiable to prevent employees who work with machinery from wearing jewellery which could get caught up in it.

Smartness
Employers may be able to justify rules aimed at achieving a smart appearance for employees, but this will depend partly on the employee’s role. For example, employers are more likely to be able to justify this requirement for a customer facing employee.

It will also depend on the nature of the employer’s business - an accountancy firm will be able to justify smarter standards than a streetwear shop.

Many rules which employers stipulate in order to achieve a smart appearance should not cause any disadvantage to employees from particular cultures or religions, for example specifying no jeans, no shorts, no vests or no clothing displaying slogans.

In which case, as long as these rules apply equally to male and female employees, no employment claims should arise.

Uniform
It is generally accepted that in the service or retail industries, a uniform is frequently necessary. However, employers should still consider whether any deviations can be allowed in order to accommodate cultural or religious requirements.

For example, allowing female employees to wear trousers instead of skirts would accommodate women who wish to cover their legs for cultural reasons.

Transgressions
Employers are entitled to discipline employees who fail to comply with the dress code. The appropriate sanction will depend on the extent to which the employee has breached the rules and any previous history of doing so.

Dismissal for breaching the dress code will be unfair (attracting compensation of up to around £70,000) unless the employer follows a fair disciplinary procedure and dismissal is a reasonable course of action in the circumstances. It would almost certainly be unfair to dismiss for a first offence.

Next steps
The key questions for employers to consider in relation to their own dress standards are: 1) why are these requirements necessary?; 2) are equal standards expected of male and female employees?; 3) Are any of the requirements likely to disadvantage employees of a certain race or religion and, if so, can any changes be made in order to accommodate these?

If an employee asks to wear a certain item for cultural or religious reasons, employers should not reject this outright, but give careful consideration to whether there is a good reason to refuse the request.

Together, these steps should reduce the risk that your business will face a claim of dress code discrimination.

Anna West is an employment lawyer at City firm, Travers Smith