[bigstrat2003]

I think that your Taco Bell example is strictly off the table. I don't doubt that some people exist who want to make it illegal to use anything but English in the US, but realistically there isn't much political will to make that happen. So we're probably talking only passing laws which restrict the government.

As far as what that means for the government, it's hard to say because of the way government is structured here. Let's put executive orders aside and say that Congress passes a law declaring that English is the official language, and that all government communication shall happen in English and nothing else. Certainly that would apply to the federal government. It shouldn't apply to the states, because the Constitution doesn't grant that power to the federal government - but we've been blatantly ignoring the Constitution in that respect for almost a century now, so it wouldn't be surprising if we ignore it in this case too. It would almost certainly go to the Supreme Court, but it's hard to say whether they would strike the law down or decide to torture the Commerce Clause even more.

If they strike the law down or clarify that it only can apply to the federal government, then you'd probably see some states pass their own similar laws (or amend their constitutions) to achieve a similar effect. But other states would still use whatever language. If they say yes, the law can affect states as well, then obviously it would. But either way I think you wind up at a point where private parties use whatever language they feel like, while government communications are in English only (at least to some extent).