What Is the Difference Between a Law and a Command?

The difference between a legal rule and a command is about the intent of the person giving the command. That's a personal relationship that, as Mark has already pointed out, is independent of what's going on in the minds of legislatures. In no legal system are the scope of legal rules restricted to the range of concrete instances which were present or believed to have been present in legislators' minds. So surely something further or more specific must be said, if disprove of non-cognitiveism or kindred theories and ethics is to be relevant to the sanction between laws, it isn't laws that ought to be?