In a number of places, Mark Murphy has defended what he calls a ‘weak version’ of the natural law thesis. His claim is that, “law not backed by decisive reasons for action is still law, but defective precisely as law”. In this paper, I attempt to provide an answer on behalf of Murphy to the question: when law is defective, what is it about law that continues to make it ‘law’ despite its being defective? Three separate, but related, strategies are examined; all three – for separate, but related, reasons – are shown to fail. The conclusion drawn is that if Murphy is unable to provide a sufficient answer to the central question of the paper, the viability of his weak natural law theory is thrown into serious question.