Do you agree with the employees or the owner?

This one is interesting. Personal opinion follows.

Language is to convey information quickly and accurately. If the employees communicate "better" between themselves in Spanish, use Spanish, however, when in front of Clients or Management or those known not to Speak Spanish, use English, as that is "Professional Courtesy." Not all words (and concepts) have direct translations, so use a pragmatic approach. But don't be rude.

On this one, I think the employees are probably "more right" than the employer, if the article is true. There is nothing wrong with converting to a more familiar language conversationally, as long as you don't intentionally exclude others. However when others are present, switch to the "business language" which in this case is English.

A civilian business can not mandate "English Only" among it's employees especially on their break time. They can mandate that English is the language to address customers in service or resolution of issues. Too many court cases rule for the employee. It would be rude for spanish to be spoken in front of non-spanish speaking. The employer can mandate that the the employmnent candidate have a certain level of english proficiency before a job offer is extended.

CCMSgt Michael Sullivan Ph.D - I see no problem with that rule as it applies to the employees language during the normal course of business. They should, however, be allowed to speak Spanish during breaks, etc.