I have the summary of a decision from ninth circuit (I think) around here because we had a question about whether it was appropriate for our staff (there are 14 languages represented) to be required to speak English at work. Basically, Englsih-language only policies are not legally defensible in the workplace and constitute a civil-rights violation even in workplaces where there is no direct customer service.
What if a state passes an "official language" law? I don't think any have them (outside of New Mexico's 2) but I remember hearing of a few states proposing them.
You could pass that as mostly a symbolic gesture, but there is a whole section of Federal Law( and I forget which title it falls under but I imagine it's civil rights) that requires that government programs (education, health, revenue, elections, etc.) must either have materials, translators or a language service available in order to offer similar services to all citizens regardless of their primary language. It is possible that this applies most specifically to Federally funded programs (I'm not sure), but most States get Federal funding for health and for education at least.