Adam breaks it down quite nicely. :first:
You must never have heard of free speech. In this awesome country, we are free to say what we like.
If you're an individual, you can say what you like (responsibly of course) and in whatever language you like.
If you're a business, your primary language between you and your clients is, again, whatever you like. However, if you want to succeed in the market, you must learn and use the prevailing language of your clients. On the other hand, clients and potential clients shouldn't get mad about businesses that let their employees speak in other languages. They should simply vote with their dollars and take their business elsewhere.
If you're the government, you need 1 (one) language by which you communicate throughout all government entities and with all that are governed. From local libraries, police, fire and other departments all the way up the chain through county and state police, state governments and federal government entities, the only language should be English. Likewise, the only way for any citizen to get help from any government entity should be in English. This includes all forms of communication from letters to email to phone calls to personal visits.