Can we tell employees not to dye their hair with bright colors?
Yes, you can tell employees not to dye their hair, but there are a few things to consider before doing so.
Employers generally have the right to set guidelines with respect to professional appearance. Brightly-colored hair is not a protected trait or class (e.g., race, sex, age). However, if it was part of a religious practice or common in a particular ethnicity, an employer would want to consider whether it would be appropriate to make an exception or accommodation. If neither of these were the case, there would be no issue enforcing a policy prohibiting brightly-colored hair.
Keep in mind, however, that creative hair colors are more common and socially acceptable today, even in professional settings. Prohibiting brightly-colored hair could make it more difficult to find or keep talented employees. It’s generally best to have a sound business reason for your dress code and appearance policy.
If you decide to implement a policy like this, make sure that your managers apply it consistently. Allowing one employee to have pink hair—when not a religious or other thought-out exception—but not another, could create workplace drama, and even open you up to discrimination claims.