There is no federal law governing employee dress codes. Employers may implement whatever dress guidelines they feel are appropriate, as long as they do not discriminate on the basis of gender, race, religion, disability, or any other federally protected status. Nonetheless, it may be best to avoid imposing rigid or highly restrictive dress requirements. Overly restrictive requirements may create resentment among employees and negatively affect morale in the workplace. Further, employees sometimes do go to court over dress codes perceived to be overly restrictive or discriminatory. And, employees who can prove that the dress code is an unequal burden between male and female employees may be able to successfully bring a sex discrimination claim. Although employees rarely win such cases, the litigation itself is costly and disruptive.
In general, courts have ruled that private employers may implement dress standards for employees as long as they can provide business justifications for them, and as long as the standards do not affect one group of people more than another.