As is the case with all federal policy, the EEOC provides a vague and illiterate policy concerning "English Only" rules for the workplace.
This creates a continual debacle in most work assignments because in the EEOC policy, they state "Circumstances in which an English-only rule may be justified include: communications with customers or coworkers who only speak English; emergencies or other situations in which workers must speak a common language to promote safety; cooperative work assignments in which the English-only rule is needed to promote efficiency."
Based on this statement, the federal government requires "English Only" in most situations due to the safety requirements applicable to vacating a building when the fire alarm sounds.
As usual, the government generates illiterate policy so that the lawyers can sue the pants off of the boss who declares an "English Only" environment.
The government also promotes such action, because they permit illegal workers to sue the boss rather than put the boss in jail for hiring illegals.