Let me turn it around and say "If it is obeyed for reasons other than it being a law, it is a good sign that it should not have been a law in the first place." Any attempt to ground law in something else than the law itself is a wild goose chase. The only justification of law is the capacity to enforce it. Dura lex, sed lex. If one does not like that, one should change the institutional apparatus that promulgates and enforces such laws, instead of bickering about their supposed logical inconsistencies. Mr. Goedel has taught us that you can find potential inconsistencies in virtually any complex system - so pointing out to such inconsistencies or contradictions is not a big deal and will certainly not cause any legal system to collapse.
Wojtek