Preventing Employment Discrimination FAQ
Are English-only rules legal?
4. Are English-only rules legal?
It depends on the purpose and scope of the rule. An employer may be able to prohibit on-duty employees from speaking any language other than English if it can show that the rule is necessary for business reasons. If your company has an English-only rule, you must tell employees when they have to speak English (for example, whenever customers are present) and the consequences of breaking the rule.
For information on national origin discrimination, including the rules on English-only rules and accent discrimination, see Nolo's article Avoiding Discrimination Based on Race and National Origin.