 And what does it mean to say that something is valid law? In effect, Ross tells us, it is to predict the behavior and thinking of courts. Details aside, to say that “X is valid law” is in effect to say that (1) judges will act in accordance with X, and (2) in so acting, they will feel themselves bound to do so. Hence, claims about what is valid law are claims about purely natural-factual states of affairs: facts about the behavior and psychology of judges (1959, pp. 42, 73–74, 75).