It depends on the question. If it's really a question about law that belongs on the — hypothetical, at this point — Law SE site, and you're only asking because the law in question happens to be written in English, I'd say it doesn't belong. If it's about the usage of language itself, then it does belong, and I'm interested already.
So, the quick test: if the law/bill/contract/whatever were written in Chinese, would you still want to ask your question? If so, it doesn't belong on this site; if not, ask away!