It starts early. This week, my son told me that as punishment for wearing his school shirt untucked, he will be missing Friday Happy Hour. He’s devastated, naturally, to be losing out on a full hour of free play on Friday afternoon – the highlight of every primary schoolboy’s week. So it came as little consolation when I explained to him that the importance of following a dress code was a vital lesson to learn and one which would most likely help him to get – and hold on to – a job one day.

There has been a fair amount in the press recently on the issue of dress at work, ranging from the absurd unwritten outlawing of brown shoes amongst London’s City elite, to the infinitely more worrying insistence on a client-facing female receptionist wearing high heels. Dress codes have also found their way to the European Court of Justice, most recently in the cases of Achbita v G4S Secure Solutions and Bougnaoui v Micropole Univers, in the context of Muslim headscarf bans and religious discrimination.

This month, ACAS have updated their best practice guidance on dress code policies, based on a research report carried out by King’s College London which examined dress codes and appearance management in the workplace and their impact on HR/employee relations.

So why have a dress code? Most commonly, employers may require their staff to wear a particular uniform in line with their brand, or dress in a certain way to project a particular professional or corporate image. Alternatively, health and safety could be the driving force behind a particular dress code.

Whatever the motivation, any dress code needs to be fair and proportionate; it must be relevant to the job and reasonable. It must also be non-discriminatory; this presents a key challenge for employers who need to ensure that they apply dress codes consistently, whilst keeping in mind individual requirements. The key protected characteristics to watch for in the context of dress codes are religion or belief, age, sex, gender-reassignment, disability and sexual orientation. Throughout the employment relationship, from recruitment to dismissal and beyond, employers should give careful thought to whether their dress code, or requirement for a particular aesthetic or appearance in their employees, disproportionately disadvantages those from these protected groups. Reasonable adjustments to accommodate a disability is another area to watch; employers should be prepared to relax or modify dress codes for disabled workers.

ACAS recommends that when drafting or updating a dress code, an employer should think carefully about the reasons why they need such a policy. Also, consultation with employees when proposals for implementing or amending a dress code policy are at a formative stage is advised. As with all policies, a dress code will be of limited use to an employer if it has not been communicated to staff, so they fully understand what standards are expected of them. This becomes especially important if the employer intends to take disciplinary action over policy breach.